exceptionally prone to seeing the scurrilous, sexy, or kinky aspect of everything; obsessed with sex; prone to seeing sexual overtones to nonsexual behavior.
A dirty minded person may be hypocritical and unctuous, but read filthy motives into the acts of other people. For example, in the movie "American Beauty," the military officer wrongly assumes that his son's interactions with his neighbor are homosexual, rather than commercial--projecting his own repressed sexuality onto others (with deadly results).
The dirty minded obscene person does not shamelessly exult in his bawdy language, nor does he use it without self-consciousness... The dirty minded person has only partially internalized the taboos that he violates...
Joel Feinberg, _Offense to Others_, p.267