The quality of the thumbnail. If it looks crude in the thumbnail, it is going to look crude full size. One important thing for me is a nicely shaped breast if it is of a woman. Breast seem to be the toughest thing to get to look realistic in Poser. If the breasts look like they could be on a real woman, chances are the rest of the character will also be realistic looking, or at least look good. Turns off are breasts as big as Idaho, or breast that stick up in the air when the character is on her back. Please, take gravity into account people.