If a mask doesn't harm the wearer, doesn't take away from the supply needed by medical and other essential personnel, and can help stop or minimize spread from asymptomatic carriers, why not wear one?
It seems that masks might harm the wearer if warn incorrectly. Well, here's some information - https://www.info.gov.hk/info/sars/en/facemask.htm - looks like there are already lots of videos as well. (And they would need to be adequately cleaned, no question.)
Taking away from essential personnel - don't think that's applicable to cloth ones.
And i think most studies show they reduce spread of viruses. Probably not eliminate, but reduce.
So, I certainly intend to wear one - I have 2 on order. And I hope others will too. It won't solve the entire problem, but it can help.