The Dallas Cowboys may or may not be "America's Team," as their management likes to suggest, but they certainly do command more than their share of national respect in the betting market.

Dallas is 3-9 against the point spread this season. The worst record in the NFL (matched only be Detroit, with Minnesota 4-8), yet the Cowboys are 3 1/2-point favorites over the Houston Oilers this Turkey Day in Irving, Tex.

That 3 1/2 figure indicates the blind faith and trust that bettors have in Dallas -- and in Coach Tom Landry. The line, and the fans' reaction to it, would indicate there is a law of the land that states that the Cowboys can't possibly lose three games in a row and four out of their last five.

The hard evidence indicates they can, and will. This Dallas team has been slightly overrated from the start. It is still a good squad, but not up to recent standards for reasons mentioned in this space last week. Dallas reinforced those observations last Sunday by losing to Washington 34-20, as a 5-point favorite, in a game that was not even as close as the score.

Past reputations die hard in the football public's mind and many fans refuse to believe what has happened. I will, accordingly, attempt to capitalize on the situation again by taking Houston for an imaginary $500, getting the 3 1/2. The Oilers' balanced offense is going to put points on the board. Only an outstanding effort by Roger Staubach and/or Tony Dorsett can halt the Cowboys' slide. Houston is a better team than either Washington or Philadelphia.

My No. 1 pick of the holiday weekend, however, is Denver, risking $1,500. The Broncos are favored by 7 at home Sunday against Oakland, their bitter rival of many seasons. Oakland defeated Denver, 27-3, Sept. 30. That was before Denver's offensive line started to give Craig Morton improved protection, and before the Broncos' superb defense got its act together.

This team is the best Denver has ever had. The Broncos should handle Oakland rather handily in their last regular-season game at home.

The week's three other selections are worth $250 apiece: Washington giving 2 at the New York Giants, San Francisco getting 5 at home against Los Angeles, and Seattle giving 6 to the New Ork Jets Monday night in Seattle.

The Redskins are 8-4 against the spread, tied with Buffalo, Denver, St. Louis Tampa Bay and the Giants for the best '79 record. Joe Theismann (I just bit my tongue) is playing smartly, leading a team that still lacks proper respect. Los Angeles can be "upset" by just about anyone these days, while Seattle figures to be steamed up for its game-of-the-year on national television.

In other games, Las Vegas lists Chicago 4 at Detroit, New England 10 over Buffalo, Pittsburgh 11 over Cleveland, Cincinnati 3 over St. Louis, Tampa Bay 7 over Minnesota, New Orleans 2 1/2 at Atlanta, Philadelphia 4 at Green Bay, San Diego 10 1/2 over Kansas City and Miami 3 1/2 at Baltimore.