I noticed that some posts I definitely already reviewed at some point show up again.
It is impossible for me to suppress these; clicking "review answer/question" increments the review count, but the post still shows up when I reload (and the review count correctly resets, which shows that at some level the system knows these posts are already reviewed).
In case a dev wants to have a look at the database, this is one of the posts that keep showing up in the low quality posts tab, no matter how many times I review it.
I do have 1k reputation and the Strunk & White badge, by the way.