It was former Florida governor Reubin Askew's turn to crow about an overwhelming straw poll victory over other Democratic presidential hopefuls last weekend, in the key state of New Hampshire, no less.

Askew stomped his presidential rivals up, down and sideways at the Manchester, N.H., Democratic Party's annual picnic Sunday, winning 1,066 votes to Sen. John Glenn's (D-Ohio) 34 and former vice president Walter F. Mondale's 14.

But was it a testament to his charisma and popularity or perhaps to the fact that he spent more than $2,000 on $3 picnic tickets that he gave away across the state, at inland senior citizen homes, coastal college campuses and upstate kaffeeklatsches?

This "picnic poll" and the publicity boost it may afford its champion point up a concern that finally may have reached critical mass among active Democrats. Only President Reagan came in for more abuse than the straw poll phenomenon at last week's meeting of the Democratic National Committee in Detroit.

Party Chairman Charles T. Manatt condemned straw polls as "divisive, non-useful, expensive and extraordinarily irritating."

Ken Melley, political director of the National Education Association, a powerful force within the party, agreed.

"If the candidates continue to pursue each other through the straw ballot process, they will be hitting away at one another in such a way as to raise doubts in all camps," he said.

Even Sen. Alan Cranston (D-Calif.), known as the "straw poll candidate" because of his success in milking political advantage out of his successes in them, has decided not to participate in straw ballots in Florida and New Jersey in order to concentrate on the one in Maine.

"We've decided not to play in those polls because they eat up so much candidate time, staff time and money," Cranston aide Rob Schroth said.

The straw polls, which have cropped up at state party gatherings all over the country this year, are simply expressions of preference, and have no part in the selection of delegates to the presidential nominating convention.

Lesser known candidates try to use them to gain credibility and name recognition, and state party officials see them as a way to attract attention and money to party functions.

"This is the first time in years the candidates have been going into states and paying attention to the party officials, so I find it peculiar to hear Chuck Manatt ranting and raving about it," a Mondale aide said. "I don't think he understands how strong parties are built."

Still, Schroth and others say that, in coming months, many such contests may sink into oblivion as the candidates begin picking their shots more carefully.

Because the straw polls vary greatly in their breadth and structure--from fund-raising dinners to controlled party operations--Democrats of all persuasions increasingly are arguing that at least the significance of each should be more carefully examined.

Aside from the financial drain and physical strain on the candidates and the divisiveness that these popularity contests are inflicting on the party months before the presidential season officially gets under way, party leaders and campaign aides complain that the press has been sloppy about evaluating them.

"Massachusetts and Wisconsin really meant something, but you people were just plain snookered in Alabama," a Mondale operative said. He was referring to the heavy network and press coverage of last month's straw poll of 124 Alabama Young Democrats, which Cranston won with 65 votes.

All three major networks reported the story in the evening news. This gave Cranston's victory an air of significance, coming as it did on the heels of his unexpected defeat of Mondale in a poll of party activists in Wisconsin a week earlier: "second major boost in a week" (CBS), "an added touch of credibility" (ABC).

The story also generated headlines in this and other newspapers. But even the Young Democrats, overwhelmed by the attention, told a reporter that "We don't represent the grass-roots."

Cranston had spent $2,000 to charter a boat to float the Young Democrats down the Alabama River the night before the vote.

When Askew campaign staffers heard about the Manchester picnic a few weeks ago, they thought they smelled another Cranston surprise in the making and figured they could play that game too, according to Askew aide James Bacchus.

"We found out it was organized by Richard Gabriel, the Manchester city chairman--a Cranston supporter," Bacchus said. "We decided to work it ourselves, primarily as an organizational test. We didn't pay anybody's expenses. No rides on the river. No free lodging," as Cranston provided delegates in Wisconsin.

Gabriel was quoted in the local press as calling the picnic poll a "significant victory" for Askew and in a small story in The New York Times as saying it showed that the former governor was more organized there than his fellow candidates.

Askew views it not as a real test of his strength in Manchester compared with that of the other candidates, Bacchus said, but as a show of organizational skill.

"We've avoided most of these events and spending all our time in New Hampshire and Iowa," he said. "Now some people are asking, 'Who was that masked man?' "

Democratic activists are grumbling about upcoming straw polls on the grounds that the rules for selecting voting delegates are confusing (New Jersey), or that the party has closed the process to almost all but party stalwarts (Florida), or that the polls are frivolous, open to anyone who can buy a $40 ticket to a fund-raising dinner (Iowa).

Maine's state party "conference" Oct. 1 and 2 could have as many as 4,000 voting delegates, including elected officials at all levels, party activists and contributors. All the presidential hopefuls except Hollings and Askew have accepted invitations to participate, according to state party Chairman Barry J. Hobbins.

In contrast to its wide-open 1979 event, Florida's Oct. 22-23 convention will poll 2,577 delegates, most of whom are party officials or handpicked by the party. Iowa's annual Jefferson-Jackson Day fund-raising dinner Oct. 8 also will poll about 2,500 paying customers.