I always learned kvetch to mean a complainer (or the act of complaining itself). I don't think this carries with it the implication that the person is unpleasant, much less lazy or absurd.
Yiddish has some of the best words for describing people and their mannerisms, some of which have been fully adopted by English, like klutz and (a little less common) chutzpah.
TIL Yiddish has a word that accurately describes a majority of HN users
I'm also fond of "[obdurate|inveterate] pedant"
In German, "Quatsch" means nonsense.
I thought of the same word, Quatsch. The Yiddish word probably shares the same roots.
I always thought it is related to "quetschen" (squeezing). A kvetsh is somebody who is being squeezed and winces or squeaks (and incidentally, to squeak=quietschen).