くせに as “and yet, even though, in spite of”
The くせに (癖に) grammar pattern and conjunction, which translates to something along the lines of “and yet, even though, in spite of, etc.” is very similar to the のに grammar pattern and conjunction which translates to something along those similar lines. The key difference between くせに and のに is that くせに is used much more subjectively and judgmentally to express one’s contempt towards something, that something being either the speaker’s target conversational partner or a third person.
When employing the くせに grammar pattern, the stem of い-Adjectives, the stem of な-Adjectives followed by the particle な, nouns followed by the particle の, and the respective Plain-Form conjugation of verbs is used.
When employing the くせに grammar pattern, the subject of the subordinate clause and the subject of the main clause must be the same entity, unlike in sentences employing the のに grammar pattern.
In its formal construction and usage, くせに is implemented when the implications of the subordinate clause do not meet their expectations. For example, the sentence
Kare wa otoko no kuse ni kaimono ga suki da.
(He’s a guy, and yet he likes to go shopping.)
*This utterance indicates that the speaker believes the implications behind being a male is to not be fond of activities such as shopping; and thus, since those seemingly implicit expectations have not been met, criticism ensues.
Kare wa renshuu ni konai kuse ni shiai ni sanka suru tsumori da.
(Even though he doesn’t come to practice, he intends to play in the match.)
Kare wa sugoku atama ga ii kuse ni taishi o idakanai.
(Even though he’s a such a bright person, he has no ambition.)
*This grammar pattern can also be used in a playful and teasing capacity.
Kare wa saitei da!
(That guy is the absolute worst!)
Suki na kuse ni.
(Even though you like him.)