Responses
Merry has a goatee list http://www.mangago.zone/home/mangalist/20277/ ^^
And my own rec would be http://www.mangago.zone/read-manga/hachimitsu_darling/ although his goatee is not very prominent it's a very nice manga
And here's also a moustache guy http://www.mangago.zone/read-manga/partners/ but I'm not sure if you'll like it xD
Oh, yeah, one more http://www.mangago.zone/read-manga/bamford_koushakuke_no_shitsuji/ (it's a sequel to http://www.mangago.zone/read-manga/no_99_ningen_omocha/ but you don't have to read it)
yaoi where the seme has a beard/mustache/goatee/etc? i can't find any really good ones, but they can just have stubble or something but it has to be prominent or where you can see it. thank you (づ￣ ³￣)づ