Sometimes I crop a thumbnail because I want to show the central theme or item which is the focus of the piece to greater effect.  I don't think of it as a "tease" so much as there is something in the piece that I hope the viewer will notice.  If they click on the thumbnail that shows that item, then, to me at least, it's more likely that they will pay attention to that part of the piece.

I could be wrong, of course, but that is why I sometimes crop.  Not often lately, but that's more because I've become lazy since the system started creating automatic thumbs.

I also don't click on images where the thumb is nothing but a content advisory.  However, there are a whole lot of thumbs I don't click on .... for me, there is maybe one image on a browsing page that will get my attention.  I don't have the time for, or the interest in, violence or t&a.  My particular interests are animals and architecture ... so full on thumbnails of violence or nudes would be unlikely to draw me in anyway.

Getting back to why I used to crop my thumbnails (before I got lazy), it was mostly just artistic preference.  Sometimes a detail that is important to the artist gets lost in the scale of the thumb.  I would hazard a guess that, other than compliance with any nudity or other content concerns, that's probably why most artists do it - if they do it at all.

Also, I post my work in order to share it with the people who care about what I do.  I will probably never be one of those artists who gets a zillion hits on every image, but I honestly don't care.  I would rather have 5 friends look at something I've done and see something special in it - or appreciate the work I put into it -- than have one NVIATWAS with a ton of views and comments like "ohhhh, she's hot!!"

That said ... there are people who put a lot of work into their NVIATWAS images, and I hope they get every hit they desire, cropped thumbnail and content advisories notwithstanding.  Just not from me, and I appreciate the fact that I no longer have to look over a ton of those images in miniature just to get to the images I would like to see.

Could be worse, could be raining.