Two things: 1. Plenty of gay people use it to describe their sexual orientation in a very neutral way, and it is often promoted as such. From the oft-used acronym LGBT to the Gay-Straight alliance, gay is not in and of itself derogatory, nor should it be dropped from neutrally describing the sexual orientation of homosexual men, at least at this point in time. It is not anywhere near on par with that other odious word to describe gay men.dsheinem wrote:"Gay" in the third sense of the term you list is a derogatory usage, meaning it is one that equates things attached to meaning 2 as "stupid" or "annoying". That usage is offensive to a lot of people (no, it is not offensive to everyone and no, it is not offensive to all gay people).
2. Using it as a slander may have well been influenced by its adoption of the homosexual community in the 60s, but in fact it was a) used to refer to homosexuals decades earlier, and b) was used as an insult centuries prior (some even think the insult goes back to the 15th century, the passage is disputed). Gay meant something frivolous, gaudy, and promiscuous, without a care in the world. As an insult, it was used to target homosexuals for being such, but it was not in and of itself derived from such.
Similarly, dim-witted for a while referred to folks with mental disabilities, but it both predated and survived that usage, as I'm sure gay will.