Traditionally, the 6th, 8th, and 12th houses are the so-called 'bad' houses in astrology. There is still a range within them, though, which depends entirely on specifics. Here are just a few of the ways I've personally seen that play out, in 'best' and 'harder' fashions:
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6th house -
Best: career in medicine, focus on animals/pets, HR career, work as executive assistant

Harder: illness, more subservient work roles than desired
2/

8th house -
Best: Psychotherapist, good money from partnership or investors, work in banking, work helping others through deeper life topics, inheritance, occasionally clairovoyance/mediumship

Harder: Death, various traumas
3/

12th house -
Best: Enjoys solitude, positive metaphysical experiences (meditation, magic, energy work, etc.), occasionally psychic, work/volunteers in prisons or hospitals

Harder: long-lasting illness, physically isolated from others, estrangement, people working against you
4/

Basically, they can still have 'bad' and 'good' expressions, and which ones are applicable to different people depends on things like sect, benefics/malefics involved, mitigations, what the house ruler is doing, who is signified by planets in the house, etc.
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So yes, one of the significations of the 6th/8th/12th is 'bad house,' but there's still a lot of variety to unpack there, and those houses can still be experienced in gradations of better or worse depending on all of those other factors.
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One last P.S. - it's essential to use house rulerships here, bc those house expressions may manifest related to others in your life, not you. Examples I've seen: loss of or estrangement from a sibling, w/ruler of 3rd in 12th. Ruler of 11th in 8th: death of a close friend. Etc.