assassinate, badmouth, blotch, fingermark, fingerprint, inkblot, libel, malign, splodge, splotch, traduce.
Your query has returned 147 words, which include anagrams of smirches as well as other shorter words that can be made using the letters included in smirches.
The words in this list can be used in games such as Scrabble, Words with Friends, Wordscapes and other similar games.