The Welshman played alongside Robinho after the Brazilian joined Man City in September 2008 for a then British record deal worth £32.5 million.
Robinho scored 14 league goals in his first season at City but only made 10 appearances in the next year, before moving to Santos on loan having failed to live up to expectation in England.
Bellamy said of his former team-mate: "The one player - and I quite liked him as a person at times - was Robinho, with all the ability he had, which was astonishing at times.
"He just let me down. I just felt he was such a top player, but, the feeling I had was he was too big for Man City at that time - and us players who were with him were lucky to be with him.
"That was a real disappointment for me."
Bellamy was then asked how he defined a 'problem player'.
He replied: "The only problems I ever really had with a player was professionalism; what time he came in, how he trained, how serious he took it, how he played.
"Does he do everything right to give himself the best opportunity to be the best player he can on the Saturday?
"If I found a certain player was not, I found it disrespectful towards myself. I saw players with miles better ability, but I see them at the same time abusing what they had.
"There were times when I know they were out on a Tuesday night and they'd come in Wednesday to training and it was just not an effort and then on Thursday it was a knock-on effect.
"As players, when you see that… I found it heartbreaking."