Its all according what part of Croydon you are talking about though, its a pretty big place. Yes Thornton Heath and the like are horrible but places like Sanderstead and Addiscombe are as affluent as you like.
I live in Horley and yes it isn't the most interesting place in the world but it is ok i mean i don't worry when my kids go out that they will come back mugged or beaten like i would in some places but it has just a mark of nothing hanging over it really.