Why are there still relatively few LGBT characters in adverts?

It's something which I've noticed personally. Even while LGBT(TQQFAGPBDSM or whichever extended acronym you may prefer) characters are more numerous and accepted in sitcoms, soaps, dramas, superhero series etc I have barely ever seen an openly gay character in an advert, apart from one blink-and-you-miss-it girl-girl kiss.

Still the victims of prejudice, or not fitting into the advertiser's intended demographics? Discuss!

The annoying Hungry House ad with the singing.

Guy with a big fat arse camping it up by himself and with other fellas in various Moneysupermarket adverts. It went beyond the uncanniness of the initial advert into full-blown mincing, pouting and strutting.

Neither are particularly representative examples. Gays in adverts are still a bit 'Clarence'.

That's a point - I forgot about them, also "ooh, it's fabreze!" man.

5% of the population is gay. That may or may not include lesbians, bisexuals, asexuals and other non-hetros. So I doubt the advertisers particularly want to target them, but also, given the short spans of the average commercial a sort of shorthand might be required in order to show that the characters are gay. If advertisers resort to stereotyping (all gay men are camp); it might be deemed offensive. The more inclusive assumption might be to not have a man who's sexuality declared and people can just assume he is whatever.