Maybe this is being a bit too anal about tagging, but here I go anyway;

With Sweat, it's more of an actual focus/fetish, as opposed to a simple sweat drop or two, which is more so just, well, a drop or two.

For example;

Imaged tagged sweat, where it can be the actual focus

post #518688

Image tagged sweat_drop, where sweat is also included

post #487869

....or people could just search sweat -sweat_drop. sweat drop is still sweat.

I didn't even know about sweatdrop. I'll start using that when I see it just so sweat -sweatdrop has a better chance of pulling up relevant posts.

Anyway, all that unimplicating it would do is people would either manually tag sweat with it or just stop using sweatdrop until someone suggests aliasing/implicating it.