its pretty obvious from consuming stamina giving exp
So, I looked through the source code, and it seems that wiki is outdated.
Here is the source of that quote: https://lonarpg.miraheze.org/wiki/Succubus_builds
And here is the source code. Code that increased xp seems to be commented out in most cases. Exhibitionism does increase xp, but only if there's company.
LonaRPG.B.0.9.4.0.5\LonaRPG\Data\Batch\Action_CHSH_Masturbation.rb
tmpBouns = 1 #tmpBouns += 0.2 if $game_player.actor.stat["Prostitute"] == 1 tmpBouns += 0.2 if $game_player.actor.stat["Exhibitionism"] == 1 && tmpSight #tmpBouns += 0.2 if $game_player.actor.stat["Masochist"] == 1 #tmpBouns += 0.2 if $game_player.actor.stat["SemenGulper"] == 1