cpl of points, the world of salsa (and other styles)does discriminate(Sorry), the politics, various instructors saying their styles are better, even in the same county, town and schools, advanced dancers being clique and not encouraging / dancing with beginners, so sorry for that but now back on topic(no discussion, it happened to me)
men hate the unknown, even dancing with a totally new partner. (also men who are part of cpls would find it very hard to dance with a sgl lady and suffer the wrath of their partner lol) race is just another factor unfortunately. when you go dancing socially are these arranged by the school/classes you go to or run on a regular basis.
even it was a class arrangement, surely the instructor / organizer could make introductions and get you dancing, otherwise can I say I admire ladies who go dancing unescorted, perhaps a local dance or facebook group with sgl dancers in mind might help you partner up.
also it might be that you are a better than the male dancers and they feel intimidated, i know i can dance but I have only been ballroom dancing for a year and would hate for a lady not to get the best of a dance if i wasn't confident
yes you may get passed over but everyone does at some point, i just hope you keep on dancing
as an afterthought, why don't you do a partner search on here or other websites for social dancing (problem solved)