The ninth National Conference on Public Gaming was held this week in Annapolis, and the tempo was upbeat. There is a feeling throughout the gambling industry that President Reagan's cutting back on revenue sharing is going to have the states hungry for new sources of money before long.

One such possible source is sports betting, now legal only in Nevada. Delaware experimented briefly with football cards, but quickly closed shop. The men who run professional sports are strongly opposed to the idea. I am, too, although not for the reasons Pete Rozelle and Bowie Kuhn are.

In theory, sports betting would be wonderful. Zillions of dollars could be collected, if it were done right. Trouble is, the states wouldn't run it right. They're too greedy. They love lotteries.

The states would advocate legalized sports betting to the public in two ways, as a means of raising badly needed revenue while depriving organized crime of part of its dollar base by shutting down illegal bookmakers.

Computer companies would help convince the states that card betting was the logical first step in football. Pick five winners against the point spread. Get 16 to 1. Perfect for the states. Impossible for the bettor.

The cards, however, would do little more than educate the public to betting and the spread. Within weeks there would be a realization, by much of the public, that betting one game at a time is a much more enlightened approach to staying solvent. This segment would eventually seek out the bookmakers, who offer a much better deal, asking the client to risk $11 to win $10.

The states would never go after the serious bettor by offering game action. They would not extend credit. They would not help get the IRS off the bettors' backs. Indeed, the computer tapes would be highly subpoenable material. The states could not, then, compete with illegal bookies.

There would be no real attempt by the states to maximize their share of the market. And they would generate countless new customers for the bookmakers. The end result would be just the opposite of what the states set out to do.

This week, I'm making three selections at $250 each and one at $500.

Cincinnati, giving four points at home to Houston, attracts an imaginary $250. The Bengals suffered a letdown Sunday in New Orleans against the improving Saints. They blew away the Steelers two weeks ago, however, and the Oilers, offensively, are not nearly as dangerous as Pittsburgh.

San Diego ($250) should rebound from its poor effort against Chicago in time to handle Kansas City. The Chiefs are getting great mileage from their personnel, but I doubt they have enough firepower to stay with the Chargers. San Diego must have a victory here at home or drop two games behind Kansas City in the AFC West. They are favored by 6 1/2.

Denver ($250) is favored by 4 1/2 over Minnesota Monday night in Mile High Stadium. The Broncos' offense has flattened out the last two weeks, but the defense is as solid as ever. No one shuts down Tommy Kramer and the Vikes. However, I do look for the Denver offense to get going again, thanks in part to Minnesota's shaky defensive play.

The $500 play is Philadelphia, favored by three at home against Dallas. The Cowboys' young secondary was embarrassed by Miami and is never really to be trusted. Philadelphia's defense is the best in the National Conference. If Ron Jaworski has a decent day throwing the ball, the Eagles will prevail.

In other games, Las Vegas lists Atlanta 6 1/2 at New Orleans, Miami 7 1/2 over Baltimore, Tampa Bay six over Chicago, Buffalo 4 1/2 over Cleveland, Los Angeles 6 1/2 over Detroit, New England at Oakland even, the New York Giants two over the New York Jets, Washington 3 1/2 over St. Louis, Pittsburgh four over San Francisco and Green Bay four over Seattle.

Last WeekSeason Totals$- 300

Season Totals $250

Last week's results: Buffalo, giving five, defeated Denver, 9-7, minus $275; Dallas, giving six, defeated Miami, 28-27, minus $275; San Francisco, even, defeated Los Angeles, 20-17, plus $250. Net for week, minus $300. Net for season, plus $250.

Won-lost record: 19-15.