I would personally not have any problems with that sort of advertising, nor with you running a campaign for a porn site.  You would not lose one iota of respect in my eyes.  I'm indifferent as far as pornography goes--consenting adults are free to do what they wish as long as no one is harmed, and if the porn is legal there shouldn't be any issues.  And if I'm not mistaken, there have been campaigns for sex-related services/sites/etc. on bitcointalk.

You'll most certainly get enough applicants.  There's been a dearth of signature campaigns in the past year, so members are slobbering all over themselves when a new one finally pops up.  There might be some people who won't join due to religious or moral objections, but I'd anticipate as many applications as you'd get with a gambling or ICO project campaign.  Good luck, bro.