Synonyms for Staining:

n.

•coloration (noun)
coloring.
•staining (noun)
maculation, spotting.

v.

•blemishing (verb)
Blotting, blistering, Flawing, Slitting, Flecking, Dotting, scratching, Tarnishing, Gashing, Fracturing, spotting, Marring, Disfiguring, Specking, Defacing, Checking, Nicking, cracking, Scarring, scraping, Hacking, Abrading, spoiling, hurting, scoring, Deforming, Kinking, Scuffing, Notching, Blemishing, Distorting, marking, defecting, damaging, splotching, Discoloring, Tainting, chipping, Freckling.
•coloring (verb)
painting, coloring, Inking, dying, shading, tinting.
•dirtying (verb)
Streaking, Fouling, smirching, contaminating, soiling, Besmirching, Polluting, Muddying, Sullying, dirtying, Smudging, Smearing, Putrefying, Befouling, Defiling.
•disrespecting (verb)
disrespecting, insulting, Disesteeming.

Other synonyms:

•Other relevant words:
maculation.