Bang Yong Guk - however deep his voice may be - is an uke, NOT a seme. I swear to God, if he did not have that voice of his, every single person would realize it too - not just the few of us who look past these things.
Have you ever seen the way Yongguk sits? Legs crossed over with his fingers interlaced neatly on his knees - like a girl.
How about Himchan? Legs wide open with no shame - like a man.
Have you seen the interactions between Yongguk and the rest of B.A.P? Especially with Himchan; they all treat him like he's fragile - treating him with care much like one would do with a girl.
The members like caressing his face and shoulder hugs for affection and you can tell he likes it more than play fighting and bro-punches.
His body is exceptionally girly for a male. Yes, he's well toned and so on but he have very feminine curves and features. His waist is slim and body evenly portioned.
There are so many more things to help conclude that Yongguk is an uke but seriously speaking think about it: If he did NOT have that voice of his, would you still rule him as a seme? Everyone I've asked this answered the same thing: No. It's his voice that puts people off of his uke role. Seriously.

P.S - bonus: Bang Yongguk even has girly s AND he's the only member in B.A.P who removes his underarm hair.