Just how would anyone but you know why you'd go anywhere? Why would it matter to you where someone else goes? If there was a way to describe this weird curiosity and the threads it repeatedly spawns, I'd tell you to Search and get the coupla hundred existing different answers saying 'different strokes' instead of waiting for the fresh crop to come in.
Try this capsule version: Hobby's all about sex, just that we collect sex, like some guys collect comics, or cars. And some guys collect car mags, and some guys go to comicons.
SCs are for guys who want their sex teasy, MPs are for the touchy-feely sensualists, Incalls are for fucking, Outcalls are for having it your way at your place.
SCs and MPs can put up signs 'cause they're legal businesses not brothels; incalls are, and so they can't; you know where you live, so you don't need a sign and it's legal there.
Perhaps you might re-phrase your question to more directly address the info you're after, like: 'Where I'm from it works liike this…. Is that anything like it does here? If not, can you help enlighten me about the whys and why nots and where the fun might be'?
Re: those pix: Some places go to a fair bit of expense and trouble to photo their girls, some grab stuff off the net. No one puts up pix that aren't hot. No one's done a study, but I'd bet if the pix are honest enough so's the MP. If 'honest enough' could be put in a paragraph, this board wouldn't have been going all this time.