main turn ons:

appealing composition
appealing contrast/tonality
appealing mood
appealing content/concept

turn offs:

so-what or just plain ugly composition
over reliance on subject matter to "make" the shot
lack of concept/idea/thought
lack of mood
obvious and unintended technical incompetence with the camera
poor printing
poor presentation
techniques used do not support the content/concept (including size of print)
photographer cannot speak or write well about the work