Nah,Yamcha is rich,a baseball player,and a womanizer. The one who was made dirty the most is actually Tenshinhan. He always trains,but he is even weaker than Krillin. About Yamcha being a cheater,well,at the beginning of the story they make clear that he was always a good looking boy,his only problem was his shyness. Resolved that thanks to his relationship with Bulma,he was more confident and that combined with his beauty and his popularity as baseball player made the rest.