Don't think that'd work; TV Tropes isn't very representative of fandom as a whole, and in any case popular works will attract more negative tropes than obscure ones simply as a function of having more eyes on the page and more fingers on keyboards. On the other hand, if the page gets locked for bickering, that's probably a good (if binary) indicator of backlash.

If you asked me to come up with a more general metric of fannish approval, I might look at ratios of fanworks to mainstream sales; that's pretty hard in itself, though, since different fandoms congregate in different places. You'll find a lot more Naruto fanart on DeviantArt than Sherlock Holmes.