The Saints have been accused more than once of being a dirty team in the wake of the Bountygate scandal, whether by fans of opposing teams or the actual media. Of course, I don't agree with them. The problem is that the media has focused primarily on the bounty aspect, which constitutes such a small portion of the pay-for-performance system that Gregg Williams instituted while with the Saints, and less on the payments for other big plays like fumbles, interceptions sacks etc. But I wanted to make sure the stats backed me up, since we already know that "seldom did a Saints-inflicted injury force an opponent to leave the field."
So I examined all of the Saints defensive penalties in categories that might indicate dirty play: unnecessary roughness, roughing the passer and personal foul penalties (no defensive players were flagged for unsportsmanlike conduct) over the past three years. I also took a look at the number of fines levied on the Saints defense by the NFL, courtesy of the website justfines.com. This information was only available for the 2009 and 2010 seasons.
Please note, these stats are for the regular season only. For NFL rankings, the higher number is better in all cases. Here's what I found...
Unnecessary Roughness - 3 penalties (3 enforced), 47 yards.
NFL Rank - 3rd
Roughing the Passer - 2 penalties (2 enforced), 30 yards.
NFL Rank - 7th
Personal Foul - 6 penalties (6 enforced), 61 yards.
NFL Rank - 20th
Defensive Fines Levied - $10,000 (1)
NFL Rank - 6th
Unnecessary Roughness - 9 penalties (8 enforced), 92 yards.
NFL Rank - 24th
Roughing the Passer - 3 penalties (2 enforced), 9 yards.
NFL Rank - 8th
Personal Foul - 1 penalty (1 enforced), 15 yards.
NFL Rank - 1st
Defensive Fines Levied - $40,000 (3)
NFL Rank - 12th
Unnecessary Roughness - 9 penalties (8 enforced), 99 yards.
NFL Rank - 20th
Roughing the Passer - 7 penalties (7 enforced), 85 yards.
NFL Rank - 28th
Personal Foul - 2 penalties (2 enforced), 30 yards.
NFL Rank - 10th
Initial conclusions: the Saints can in no way be considered a heavily penalized team compared to the rest of the league, perhaps with the exception of roughing the passer penalties in 2011. They're middling on the whole and there are certainly no red flags or anything you could point to as evidence of the team being dirty. If there was any other dirty play that was never penalized, well, that sounds like a problem for the NFL and it's officiating crew.