I've been considering a buff to keep bugs out of my mouth and nose when cycling, but I've just spotted this thread and thought a shemagh may do instead. Does anyone else use a shemagh in that way?
No but I do use a buff in that way. The problem with breathing through material is that it rapidly becomes wet. When wet it is cold and harder to breathe through. The thin polyester microfibre of the buff doesn't hold water, is easy to breathe through and dries quickly. Also not too hot in summer.
A proper mask is better, but for me with my limited amount of cycling it is overkill and bulky.