When it comes to betting on the NFL, there is nothing more frustrating than an inconsistent team. If a team is just plain bad, or they are almost unbeatable, then it becomes relatively simple to make decisions about the games they are playing. If a team is great at home, or lousy against teams that can run, or their likely effort is somehow obvious in another way, then we can be comfortable in our selections. Some teams, however, completely defy our expectations. When we expect them to win, they lose. When we pick them to lie down and get rolled over, they step up and win big. Those teams are hard on your wallet, and bad for your blood pressure. The best approach is probably to avoid them until they can string together a few consistent efforts in a row. Here are the five teams that have proven in the first half of this season that what they do in one week has no effect on how they perform the next week:

New Orleans Saints - Over the course of the first four weeks of the season the Saints were betting superstars. They covered all four games, regardless of whether they were favorites or underdogs. Since then, however, they have been a disaster. They are 2-3 against the spread, but they have alternated covering and not covering each week since that hot start. Two weeks ago they blew away Tampa Bay as favorites, but then they lost to Pittsburgh and couldn't cover as a 6.5-point underdog. They have been inconsistent at home, and no better on the road. They have been a coin flip.

There has been one way to salvage some profit from the Saints during this stretch, however. Their offense has been pretty good, and their defense really hasn't, so the team has gone over the total five weeks in a row. They play the Bengals this week, and Cincinnati seemingly has no defense, so it seems likely that the over trend could continue again.

New York Jets - The Jets are a surprising 6-3 ATS, so it would seem that they have been friendly to bettors. It's the placement of those losses and the way that the team has responded to them, however, which has made this team a challenge at the betting window. After a nice win over Buffalo, and a very solid loss to Indianapolis in weeks three and four, it was easy to believe that they looked attractive as a seven-point favorite in Jacksonville. They lost 41-0. They came back with good wins against Miami and Detroit to restore confidence, but then they forgot to show up in Cleveland and lost. With losses on the road in Cleveland and Jacksonville, it then might have made sense that they would struggle playing the Pats in hostile Foxboro. They were 10.5-point underdogs, so they went out and won the game by three. This week they play Chicago at home, and, based on past performance, absolutely any outcome is possible.

Denver Broncos - Denver has a 7-2 record and is going to be a major factor in the AFC, but their betting performance has been as good as their quarterbacking - pretty dismal. They didn't cover their first two games, covered their next two, then have alternated betting outcomes since then. Part of the problem has been Oakland. They have played the pathetic Raiders twice and haven't managed to cover either time.

The Broncos present a problem in large part because of that bad quarterbacking. Jake Plummer usually seems to do enough to win, but he certainly doesn't do more than that. The offensive problems mean that they have failed to cover the three highest spreads they have faced as favorites. Before you get too excited, though, know that they have also failed to cover spreads of three and 3.5 as the chalk, so you can't just back them when the spread is low and avoid them when it is high. The team has been a better bet on the total, going under in seven of nine games. Even that has faded of late, however - they have gone over twice in the last three.

San Francisco 49ers - At 4-5 (and 5-4 ATS), this team is much better than most people expected them to be. The problem, though, is that when they lose they really lose. Their four ATS losses have been by margins of 14, 41, 29 and 31 points. After allowing 48 points to San Diego and 41 to Chicago in consecutive weeks it would have seemed that the over and the opponent were both good bets, but then the defense was incredible as they beat Minnesota, 9-3, to obviously go way under the posted number, and then the D was good again against a reasonably good Detroit offense.

The key to the 49ers defense is the running game and Frank Gore, but even his performance isn't a great indicator of team success. They have covered in his three best games, but they also won and covered in his worst game of the year. To make handicapping them more difficult, Gore is questionable this week with a concussion. Their game against Seattle is already a handicapping mess because of the potential return of Matt Hasselbeck and Shawn Alexander.

Dallas Cowboys - The best part of watching the Cowboys this year is seeing Bill Parcells age noticeably in front of our eyes. You can't blame him if he isn't having fun this year. The Cowboys are truly the Dr. Jekyll and Mr. Hyde of the league. When they win, they win by a lot - 17, 21, 28, 31 and 17. Their losses are often just as decisive, though - they've lost by 14 twice. When they play like they did against Carolina or Arizona it is easy to believe that they are among the elite teams in the league. Sandwiched between those performances, however, was a frustratingly poor showing against Washington.

Since their bye in week 3 the Cowboys have followed every win with a loss. Making them even more frustrating for bettors, all four of their wins have come in games in which they were favored. That doesn't mean that they are bad favorites, however - they have covered the four biggest spreads they have faced. This week they are likely to be the underdog as they host Indianapolis. They have only been the dog once this year, by 4.5 points against Carolina, and they won that one by three touchdowns.