Well, I guess it also depends on how you define bunny hopping.. For some it is just jumping repeatedly to gain speed. Others do all these weird little tricks where they look in circles to gain extra hight in the jump or something.
I bunny hop in the jumping repeatedly fashion. No tricks, just bouncing along... I mean, lets face it, as a skulk you have to bunny hop. It doesn't matter if its to gain speed or something, if you run right up to a marine you are dead. Moving is life as a skulk, thus bouncing is an important thing to do