A bedroom, like a bed, symbolizes your reproductive system, sex, rest, meditation and astral activities. See Bed.
A bedroom symbolizes your reproductive system as sexual activity takes place there.
A communal bedroom indicates the uterus in particular as the uterus is the only place in the body where another person can sleep.
A dirty bedroom indicates you see sex as dirty. This could be due to an overly strict or religious upbringing that puts a stigma on the sexual act.
A stain on the bedroom floor indicates you feel guilty with regard to sex. This could be due to an overly strict or religious upbringing that puts a stigma on the sexual act. It can also be triggered by strong religious beliefs where indulging in pleasures of the body is seen as evil.
Bedrooms are also a place for rest and sleep and as such can symbolize meditation and astral activities. When this is the case, other symbols in the dream will indicate which activities.
Someone breaking down your bedroom door to attack you can be indicative of sexual abuse.