As far as I remember the thug/bad boy theme is not limited to the "black gay porn", e.g., think about Triga (white British scally boys) and Citébeur (French men of colour). As Wikipedia aptly puts it "Citébeur films also include a play on fetish, fantasy and stereo-typical perceptions by non-whites of the of ethnic man: work-horse, well-endowed genitalia, urban style clothing, liaisons in the unknown poor and dangerous suburbs of large cities, interracial sexual relations, thus popularising such imagery amongst the homosexual population and promoting greater visibility and a more positive attitude towards minorities of ethnic background." While I do not necessarily agree with the "promoting a more positive attitude" part, playing with stereo-types is obviously present in the Citébeur films. As far as I understand this can also be said about the black gay porn.