Not a thing. All possible reasons that can make a fan can stop liking a team do not matter to me:
-If a player committed a heinous crime such as murder, he would be immediately banned from the NFL. And it's ridiculous to blame a franchise for the actions of one. In the 1990's, the Panthers had a receiver named Rae Carruth that was convicted of murder. Few associate the team with that.
-If the team moved, as a fan in the northeast, it would not matter to me. They are America's Team, whether they play in Dallas, Las Cruces, or Kalamazoo.
-Lack of success bothers me, but not enough to stop liking them. I have been a Cowboys fan too long. I've seen them win Super Bowls, I've seen them hit bottom. I will never throw away all those years of glory (and suffering) now.