Yes he had a bad reputation while in Portland. To be fair, though, two extra points: (1) most of the big name players on the Blazers during Miles' tenure there as a player had a bad rep (Sheed, Randolph, Q. Woods, Nick Van Exel, Bonzi Wells, Jeff McInnis, Ruben Patterson). Some of those players have been able to turn their acts around after leaving the Blazers. (2) By all accounts Miles showed up in Boston ready to work and tried hard. Physically, though, he just can't do it because of the injury.
I am not trying to stick up for Miles. I just hope he catches on somewhere and is able to play again because it looks to me like he has turned a corner. He could just as easily accept his pay check and stop playing, but he has decided he wants to keep playing despite the odds and kudos to him for that.