Do yellow braces make your teeth look moldy?

Colors: Braces come in a variety of colors and if yellow worries you aesthetically choose clear ones so that only the wire shows. To answer the question no.

They shouldn't: No, yellow braces should not make your teeth look moldy. I am assuming by yellow braces you mean some of the clear braces which have a light yellow tinge. These braces are made of ceramic, which are color stable, however, if your orthodontist uses elastic ties to tie the wires, these may discolor over time and become "moldy" looking. Get these changed at every appointment to avoid this.

Not if you brush : Any braces can make your teeth look 'moldy' if you don't brush and use floss threaders to clean the plaque from the brackets of your teeth. Also, if you do not brush well, you may have white, chalky rings left on the front surfaces of your teeth after the braces are removed.