The biggest issue is when guys use new incoming female employees as dating prospects because they don't meet females elsewhere. They may be nice and friendly but I don't want to have to shake off and turn down 6 guys who are fighting to get at me first everywhere I work, its really not ok. It happens at every place I've ever worked and watch the same guys do it to new girls. They are here for a job, not to supply you…
Realistically, you speak to different genders differently without realizing it, but I have always worked in highly-diverse environments (I wouldn't want to ever work somewhere where I saw all XYZ gender or race working there) and it has been fine.