The point is a good one, if you think about it ALL insults are derived from negative connotations. Otherwise they wouldn't be insults. It is however "case sensitive" for example if I knew someone on here (or they knew someone) was a Mongoloid - I would refrain from using the term "mong". In the same way people throw about "retard" - (which of course refers to someone with a limited mental capacity) that could be hurtful.LOL. Comedy gold.
Going on the premise that we are all football fans (and as such the "banter" and level of insult we all are party to is higher than other aspects of society) I think certain terms are accepted somewhat easier.