Some would call it slutty, but I love it. I wouldn't be ashamed being seen in public with any girl wearing a white blouse and black bra. I've even seen a girl wearing a black shear blouse and a white bra. Some girls know what a guy wants to see.
I just saw a girl today in bangalore near ITPL. She is wearing a black bra under her cute white front button shirt, I would say she was around 34C or 36A.. Its was damm hot, that my weapon got tempted to see her breast and bra cuts.. She was so hot and I am going to come tonite ;-)
Girls, please continue wearing similar to this.. We guys need you ;-)
I think it's pretty tacky. I've been seeing this more than I'd like around campus lately and the general impression it seems to have on my guy friends is she's the kind of girl they'd only want for a night. I think subtlety is key, slight cleavage, a shirt that falls off the shoulder a bit, etc. These things look unintentional but still attract attention, wearing a white shirt with a colored bra looks like you're trying way too hard to get attention. Desperation is never attractive.