as a straight male i can't give a specific answer to that, its just like, well she's a girl and has all the attributes i like from a girl (feminine, huge breasts huge ass whatever), and then in top of that they have a dick which tbh is pretty neat, she definitely a girl but then she can cum and all that shi, i don't feel attracted to men, at all, NEVER, however specifically dicks in a woman its like a pass, i hate gay porn, but if its a girl with a dick it's sort of more acceptable, and also is sort of really really popular so if you like hentai you can't really get past futa, it's extremely popular, so i also got kind of accustomed to that, because the artists that draw futa are EXTREMELY talented, the more you watch the more that is like "meh its fine", i don't have fragile masculinity i know i don't like men, and futa irl i would definitely be afraid as you say, but in fantasy like porn, or hentai, i don't really mind if a girl has a dick, in fact for me is a plus because like i said, all the woman attributes i feel attracted to, and then in top of that she has a D and she can fuck other woman or she can cum.
now i am really weird because i like futa, but then it doesn't really get me going when by example a girl is fucking a man with her idk 1m long dick that's really weird, so my "rules are", futa x woman fine, futa x futa fine, futa x man fine AS LONG as she ain't shoving his dick in the man thats just getting into the gay zone i don't like it i don't feel comfortable with it no matter how hard artists want to implement that i'd just ignore it, i'm a weird example ik but in conclusion, i like futa because i like woman and if a woman has a dick it's not really gay and its a plus because then that woman can fuck other woman which leads to REALLY really crazy art i've seen around it, more than wondering if im gay im starting to wonder if im addicted to porn because boy that shi gets me going.
and what i've explained doesn't mean i dont like normal porn, its more of a "if she don't have dick and its really good art thats great, if she has a dick and its really good art thats great", i don't have a preference its just like the one that gets me going the most is best, and futa just also happens to be on the list because its not gay shit and most of the time its not a woman shoving her dick into a man either (most of the time, there are some times that it is like that and i don't really like that because then it starts being gay like wow you like this art where a man is getting a dick shoved? no thanks thats why i know im not gay im not that gone lmao)