Yes, SMEARS is a Scrabble word!

Letter values in Scrabble US: S 1, M 3, E 1, A 1, R 1, S 1.

Is it a valid word?

SMEARS is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

slanderous defamation
a thin tissue or blood sample spread on a glass slide and stained for cytologic examination and diagnosis under a microscope
a blemish made by dirt
an act that brings discredit to the person who does it

stain by smearing or daubing with a dirty substance
make a smudge on; soil by smudging
cover (a surface) by smearing (a substance) over it
charge falsely or with malicious intent; attack the good name and reputation of someone

Also: cytologic smear.

Not playable in Scrabble US: MALIGNMENT, CYTOSMEAR.