Same reason once perfectly acceptable words like queer and faggot are now slurs
the word doesn't matter, the manner in which it is used does.
( Peej, Tue 26 Feb 2013, 10:30, 1 reply)

i dont think queer or faggot were ever acceptable
some gays blokes called themselves queer in the 60's but its only acceptable from another 'queer'

white blokes cannot say 'my nigger' as a friendly term to a black dude, but another black dude can
( spimf ™ is whoever you want him to be, Tue 26 Feb 2013, 11:00, closed)

queer and faggot have meanings other than the derogatory ones you refer to
they haven't always been slurs you faggot
( The Doveston haunted by the memory of his own amnesia, Tue 26 Feb 2013, 11:10, closed)

well...
dictionary.reference.com/browse/queer

dictionary.reference.com/browse/faggot+?s=t

however

en.wikipedia.org/wiki/Faggot_%28food%29

i would be offended by being called a faggot of the pork variety (not because I'm kosher or halal) but because its a shit version of Haggis the 'great chieftain o the puddin race'

if you're calling me faggot as in gay - i have shagged your dad AND your mum. so technically i would be bi.
( spimf ™ is whoever you want him to be, Tue 26 Feb 2013, 12:01, closed)

your dad fucking loved it by the way. the faggot

( spimf ™ is whoever you want him to be, Tue 26 Feb 2013, 12:03, closed)

i don't get your point, are you posting links to prove my point?

( The Doveston haunted by the memory of his own amnesia, Tue 26 Feb 2013, 13:15, closed)