He's pissed off at his former team, bawdy and brash enough to yell at and/or about his entire team during practice (including the owner), and has already "confronted" his new starting quarterback as to why he had so much success picking him off (four times) before he came to Atlanta.
Asante Samuel was considered expendable for a Philadelphia roster replete with costly defensive backs. In Atlanta - where he was "stolen" for just a seventh round pick - he can help bolster the team's interception count (19 last year, with a good bit of that coming from linebackers) and maybe most importantly the overall attitude of the club (quote courtesy of the AJC):
"My thing is that I have to go out there with my little swag," Samuel said. "I've got to look good, feel good, smell good every day and play good. That's how I approach the game."
That approach, nicknamed "cocky and arrogant," or "C&A," has found no resistance from Mike Smith, Arthur Blank and new defensive coordinator Mike Nolan. Maybe that's because Samuel has the resume to merit such behavior, but maybe it's because that this Falcons franchise, so averse to internal strife in the post-Vick era, needs some of the attitude it's so carefully avoided while rebuilding into a perennial playoff team.
No one's looking for a cancer, but Samuel might be the first drag off of cigarette this locker room's needed to toughen its attitude.