赤 is generally understood as meaning 'red' (which can explain combinations like 赤子 (red face of a crying baby)). However, I have seen some words with 赤 that have a negative meaning, 赤 possibly increasing this connotation. 赤裸裸 (blunt, frankness (赤裸 being nudity in Chinese)), 赤貧 meaning extreme poverty, 赤口 (赤日?) being one of the unlucky days in Rokuyo (lucky and unlucky weekdays in simple), meaning 'Evil day'. Why does 赤 appear in such morbid and negative words? Is 赤 simply 当て字 or does it have any meaning or semantic reason for being in words like these? Is it 虫 where the common understanding of the word (in the case of 虫 it would be 'bug') has a connection to the negative meaning, if this is the same for 赤 then how is it connected to the negative meaning?
I do not know that much about Japanese kanji, but in Chinese 赤 has the second meaning of "bare, exposed". 赤貧 thus probably means "with totally nothing".