Football fans know all about traps. A defensive lineman is "invited" into what appears to be a promising situation only to discover, too late, that he's been set up by the offense. The back runs through the hole the defensive lineman so happily created. it7s a real sucker play.

Fans who follow the point spread on NFL games also know something about "traps." The line on a particular game is made to look so inviting they can't resist. A game in which they had no early interest suddenly is turned into an attractive betting proposition.

This week's card offers an excellent example. The St. Louis Cardinals are favored by 3 1/2 points at Philadelphia. That number looks low, but the professional linemakers in Las Vegas chuckle when that is brought to their attention.

"Sure, it looks like a trap. All you have to do is jump in," one said.

The Cardinals have been outstanding the last three Sundays in defeating the Cowboys at Dallas, Chicago at home and Washington at home. The Eagles are 4-4, but their victories have been over Minnesota, Buffalo, Indianapolis and the New York Giants. They have yet to beat a team with a good offense, and the Cardinals' offensive unit is one of the best.

So I'll take the bait, the Cardinals giving 3 1/2, but only for an imaginary $250. I've been blindsided too many times in the past to risk more.

The line this week finds Pittsburgh favored by 2 1/2 over Atlanta, Miami 17 over Buffalo, Cincinnati 4 at Houston, Dallas 10 over Indianapolis, the Los Angeles Raiders 6 1/2 over Denver, Green Bay 2 1/2 over Detroit, Chicago 6 1/2 over Minnesota, Cleveland 1 1/2 over New Orleans, New England 3 over the New York Jets, San Francisco 3 at the Los Angeles Rams, Kansas City 6 over Tampa Bay, Washington 6 1/2 at the New York Giants and (Monday night) San Diego 1 over Seattle.

I'll take San Francisco, Denver, Seattle and Washington for $250 each, Chicago for $750.

The Rams have played surprisingly well behind Jeff Kemp since Vince Ferragamo was injured. Then again, even Kemp had to be an improvement. It is the defense that keeps the Rams in good shape, at 5-3. But I doubt that John Robinson's defense can stop Bill Walsh's club. Joe Montana against Kemp is a mismatch. Give the 3.

Denver keeps winning with its defense, at 7-1, as John Elway continues to struggle. The Raiders, however, are life-and-death to cover the spread any week. They probably will win, but I can't see them blowing away the Bronco defense. Take the 6 1/2.

Seattle is another defense that holds together. The loss of Kellen Winslow will affect Dan Fouts' passing game. The Chargers' defense never stops anyone in game-winning situations. If the outcome comes down to the final drive, as is likely, the Seahawks will prevail. Take the point.

Washington was a trifle flat in losing to St. Louis, but the Cardinals played superbly. Now the Redskins meet a team that can't run the ball, which means the Giants' outstanding defense must get the job done. That will be tough to do against such a diversified offense. The loss of center Jeff Bostic is going to hurt the Hogs, but Joe Gibbs knows how to make adjustments. Give the 6 1/2.

The Bears still are underrated. How else could they be less than a seven-point favorite over Minnesota? Viking quarterback Tommy Kramer suffered a slight shoulder injury last week and is questionable for Sunday. His backup is Archie Manning. Poor Arch! Chicago generates the type of pressure defense certain to give either quarterback problems.

Give the 6 1/2, gladly.