Cropped and altered thumbnails are and edited alternative to the main image.  They are no more a "deception" than an edited version of a story is a deception.

If I had a main image with nudity and violence and my thumbnail image was of a cute bunny that was not even in the main image .... that would be a deception.  Arguably, even if the cute bunny was in the image ... you might say it was a deception because the bunny was not the focus of the image.

But, editing something, whether for brevity, to highlight, or for clarity, is in no way, shape or form a deception.

I am not particularly "upset" with nude thumbnails myself.  I find most of them to be a boring parade of the same old stuff.  Same with the violent stuff .... it's mind numbing in its lack of imagination for the most part.  That doesn't upset me .... I just don't care to be bothered with it.

Even an eye or a toe that is a thumbnail for a nude or violent image is supposed to be tagged for content.  So, I don't see someone clicking on an eye and getting the shock of their lives when the eye turns into giant boobies.

And, I don't have the "no nudity" filter set on my machines simply because Renderosity has a different definition than I do.  It is ever so much stricter.  They would consider a stone statue with no actual nipples or genitalia to be a "nude."  I wouldn't.  So, I don't bother with the filter because it screens out things I personally don't think need to be screened out.  It's a personal decision to leave the filter off.

It's also a personal decision (as an artist) whether or not to have a full image in a thumbnail or to highlight some portion of that image.  To make a blanket statement that it is always a deception is to imply that you know the intent behind someone else's artistic decision ... I doubt you meant to make that kind of statement, but you managed to do it.

Could be worse, could be raining.