Where would you draw the line?
I would say pictures in which the enhanced portion is the boobs. Slimming the waist, airbrushing, etc. are common even in mainstream media. Morphs would be things done with the intention of appealing to the likes of us. It would also serve the purpose of making sure that when you click something in the "Models" section, you're getting a real girl with good quality pics and not having to sift through a bunch of low quality edits.
Yeah, there's a difference between morphs and general photo retouching, for sure. Also, it's not really surprising when you see heavy retouching in professional model shoots, the intention of the picture is to create an idealistic woman, as long as it's not excessive or poorly done, I think most people don't mind retouching, it's just a part of the industry now. Self-taken camera phone/digital camera snapshots are different...the intent of those photos is to display the person as they look naturally ("here's a picture of me right now in the real world" rather than "here's a picture of me after 3 hours of styling and makeup, professional lighting and photography and some retouching"). Manipulating a snapshot defeats the entire purpose, it's attempting to portray an altered version of yourself as your natural look. Retouching of pro shots are "exaggeration", manipulating a snapshot is a lie.