Far be it from me to be a kill-joy. But before putting your chips down on a gambling stock, a strong word of caution, friends. I've done some checking, and there could very well be big disappointments in the wings that could have a decidedly nasty effect on the gaming shares. In brief:

The next critical moment for the gaming industry and for its stocks is Nov. 7, the day Florida voters decide whether they want casino gambling in Miami Beach. As we went to press, the polls showed the vote too close to call.

As it turns out, though, even if the gambling referendum is approved, there are strong negative factors at work that could blcok casino gambling effectively for several years. And these forces include the very man, state Rep. John Ryals of Brandon, who will head the legislative group writing all new gambling legislation. Ryals strongly opposes casino gambling.

Although some companies have been saying (both publicly and privately) that they expect to open an Atlantic City casino next year or in 1980 at the latest, don't bet your last buck on it. Top regulatory people both in Nevada and in Atlantic City tell me they don't see a second Atlantic City gaming operation opening before late 1980 or some time in 1981 at the very earliest.

Although it's widely believed Resorts International will be granted a permanent gambling license in Atlantic City - it currently has a temporary permit - that by no means is a sure thing. A permanent license could be decided upon in November or December following completion of an intensive, ongoing state investigation into Resorts.

The license requires the approval of at least four of the five commissioners of the New Jersey Casino Control Commission. And one of those commissioners, Albert Merck, of the founding family of Merck & Co., told me the other week: "There's no longer any assurance now that I will vote for a license for Resorts . . . because they're gouging the public."

Should Merck (who voted against casino gambling) simply abstain from voting and be joined by just one other abstention or by a rejection, Resort's casino would be taken over by a conservator who, in turn, would be empowered to sell it and turn proceeds over to Resorts.

But if there is such a problem. Wall Street's buoyant earnings estimates.

Back last May, just before Resorts' casino opened in Atlantic City, James Crosby. Resorts' chairman, told me he thought that a Street estimate of $7.40 a share for 1979 - the first full year of operation for the new casino - was a realistic assessment of the compa- hy's prospects. Obviously he was playing it safe, because it's widely expected that the big gross win should produce 1978 profits of more than $10 a share. (The company earned 78 cents a share in 1977).

For an update. I buzzed Crosby, who was feeling pretty good. I can't blame him; I would too. JUst two years ago, his roughly 210,000 shares of Resorts' Class A and Class B stock were worth about $420,000. The current value of Crosby's shares has skyrocketed to roughly $50 million (Class A $132 and Class B $242 a share). Infact, while I was editing this story, I had to keep changing the amount of his net worth almost daily. It rose about $23 million in just about a week.

Although he was reluctant to talk figures, Crosby - commenting publicly for the first time on next year's prospects - told me he wasn't uncomfortable with Street estimates of $22 to $23 a share for 1979. He hastened to add, though, that there is still the uncertainly of how Resorts' Atlantic City casino will fare in the winter months. A period of reduced gaming activity is almost a certainty during the winter, and this reduction could cut heavily into the casino's hefty pretax profit margins which, I'am told, are presently running above 60 percent.

In assessing the future of Resorts, one clearly has to took beyond the explosive earnings growth that is likely to occur over the next year or two. Such growth is almost certain to diminish sharply in the face of rapidly rising competition from other Atlantic City casino operators over the next several years.

So the obvious question is, what is Resorts going to do with its sizable cash flows?

With Resorts owning or having options on 27 percent of the commercial on 27 percent of the commercial area of the Boardwalk, as well as extensive other real estate holdings in Atlantic City estimated by some to be worth in excess of $150 million, this obviously will be a major area of development by the company. Crosby agrees, pointing, among other things, to the prospects of joint ventures with other companies. He also says he expects Resorts to have a second Atlantic City casino in operation by 1980 at the latest.

Aside from gaming, Resorts is looking into the airline business for possible diversification. Crosby says Resorts may acquire or start an air service devoted to private charters. At present, Resorts runs a small airline that operates between Florida and the Bahamas and at one time (when Resorts was called Mary Carter Pain Co.) tried unsuccessfully to take over Pan Am. "I'm devoting a lot of time to expansion; we're not standing still," says Crosby.

In analyzing the outburst of enthusiasm for the shares of just about anything related to gambling it is reasonable to assume that at least part of it - aside from the numbers at Resorts - reflects a more liberal attitude toward gambling both by local government and by the public. Passage of Proposition 13 clearly signaled the public is fed up with rising taxes and is likely to be willing to accept less painful - perhaps even objectionable - methods of tax collection.

But even gaming experts are quick to point to the danger that Resorts' performance in Atlantic City has raised false expectations. For one thing, it's pointed out that in the 115 casino operations out that in the 115 casino operations in Nevada that do at least $1 million in annual revenues - there are 273 casinos all told - the average pretax profit margin last year was 11.3 percent, roughly the same as the Fortune 500. Hardly a bonaza. So Resorts, with its monopoly and its big numbers, is the exception, rather than the rule. And even Resorts' earnings could collapse at any time.

Further, some experts believe that by the time the fourth or fifth casino opens in Atlantic City, New York may already have approved casino gambling as well. This leads one expert to remark: All that may be left for the late entries in Atlantic City will be the left-overs, since New York will pose a serious competitive threat."

Both Harold Vogel of Merrill Lynch and Lee Isgur - a top gaming analyst at the Mitchell Hutchins division of Paine Webber - believe the best way to play the gambling phenomenon over the longer run is to put your chips on four companies: MGM, Hilton, Harrah's and Bally. However, Isgur regards each of them as vulnerable for now. Another Isgur favorite: Showboat, which he regards as a takeover candidate.

Speaking of Bally, the nation's largest slot machine maker. I recently ran into its chairman, William O'Donnell who seemed euphoric. He owns 971,000 Bally shares which, as of about two years ago and at a price of about 5 1/4, were worth roughly $5.6 million. But like Resorts, Bally's shares have also shot up - to about 68 at press time: And so, O'Donnell's shares are now worth about $66 million.

Bally was in registration at the time with a $30 million subordinated convertible debenture offering, so O'Donnell couldn't talk about the company's prospects. I'm told, though, on the very best authority, that Dally's top management - assuming a full year of its Atlantic City casino operation expects to earn between $7 and $8 a share in 1980. This is based, I hear, on the prospect of $3.50 a share from existing operations at that time and the expectation of at least 25 to 30 cents a share a month from the casino. I'm not about to say no, and I wish Bill O'Donnell good luck on his goals. But first, let's see if Bally's casino is open a full year in 1980.

Where the gambling craze - some call it a madness - goes from here is anybody's guess. But several people I spoke to - among them hard-nosed Stanley Sporkin, the Securities and Exchange Commission's enforcement chief - were quick to raise the moral issue. "The amoral aspects are frightening," Sporkin says. "We have a clash between the state's responsibility to protect the public and our going to bed with the enemy . . . because the state gambling authorities will employ the same questionable techniques now used by organized crime to get people to part with their money. It's an amazing, ironic parodox that everybody [the cities] is trying to take the painless way to solve their financial ills, appealing to the lowest human instincts. It's scary as hell, because you have to wonder whre we're going. I ask you; Is legalized porstitution next?"