What drives a poor reputation for the Rogue class?

[QuickLyRaiNbow]

My sympathies.

Anyways, how about poisons that reduce the target's prof bonus.

I like it, but it's a little... book-keeping-y. It works well against players, but I think it'd be a bit fiddly against NPCs, where it's often not stated what their proficiency bonus is or what it applies to. The DM would have to back-calculate the bonus and where it applies before it could take effect.