Most of my "bad" reports are from unintended duplicate reports for spam. Once you've reported enough barely coherent one or two line nonsense, it all blends in to one, and I find myself forgetting which posts I've read and reported before.
Dont worry about that , happend to me also from my 40 bad reports are i guess 20 for double reported because i lost the line where i was reporting
If you report Mega spam threads and dont know where you was just check the last names on your report history , helpd me a few times to avoid double reports !
Anyway as long the bad reports not more as the good reports should be all good and i wouldnt care about !