My exp has been the more str8/masc the guy, the quicker their legs go up in the air - I've fucked cops, sheriffs, firemen, bodybuilders, construction workers/contractors, etc. - sooner than you'd think, they are face down on their belly and/or on their back, legs on my shoulders, taking my big dick up their ass and loving it - I think it's a power thing - most of these guys are "in charge" in professional life, so behind closed doors in their personal life, they get off and/or are intruiged about letting go and giving up control, esp of their mouth and hole - just my two cents.