Nutpicking

Nutpicking, named in analogy to "nitpicking" and "cherry picking," is the logical fallacy of smearing a whole group of people by finding a few extreme examples, typically in open comment threads, and holding them up as representative of that group. Nutpicking is similar to the straw man fallacy; the difference is the difference between attacking an argument that only a few extreme people use and attacking an argument that no one uses at all.