Forgive me if I'm off here (I don't pay a lot of attention to Pacman) but if memory serves wasn't his last kick to the curb as much about his performance (or lack thereof) as his behavior? I seem to recall that he did next to nothing for his last team.
As for the Bengals bringing him in for a tryout I am not going to give them a hard time about it. If they look at Pacman Jones, Matt Jones, and Donte Stallworth and just one of them actually has finally got his head on straight and works out for them then I say they are just doing their due dilligence and turning over every stone to find players.
I don't have a problem with teams giving players second or third chances. I have a problem with teams that don't part ways with a turd when they can confirm he's a turd whether it's his first chance or his fourth.
Think of it like this. You choose to draft a guy who is less than a good citizen because of his ability. You're taking a chance and if you're wrong then you're the one who's going to pay. So you guess right and he does fine. Great, he changed his ways. If you guess wrong though you should be ready to cut the guy regardless of your investment.
Then he gets a big punch of reality in the face and goes looking for a second chance. I don't begrudge almost anyone a second chance. People change, people grow up. Nobody's perfect and most people I know have gotten something right on their second chance at it. So another team looks at him and says "He seems to have learned his lesson, give him another shot because he's still got mad talent and we can get him for a relative bargain". Excellent. If he learned his lesson then great. If he didn't though that team should be even quicker to send him packing. They risked less (hopefully) and should be less tied to him.
Third team comes along and this guy is a known problem but still, if they want to work him out, invite him to camp, sit down and talk to the guy and see where his head is I'm not going to mock them for it. Not unless they overpay or sign him and then accept him as a turd into their midst.