I’ve posted on the “why” before:
Not all clients (MOST!) are as well informed and aware as those of us here in these forum
Many inexperienced, scared, horny (letting the little head make decisions) clients will just go ahead with a male to male encounter even if it’s not the advertised person
Many inexperienced clients would be too afraid to make a scene and say “leave, faker!” fear of getting outed as a male client, etc.
Lotsa other reasons these advertisers with fake pics get away with it.