Puddle of Mudd singer Wes Scantlin is behind bars in L.A. ... after allegedly vandalizing his neighbor's property WITH A BUZZ SAW ... TMZ has learned. Law enforcement sources tell us ... Scantlin and his neighbor have been feuding for a while -- and it all came to a head this afternoon when Wes allegedly whipped out a buzz saw and went all Leatherface on the neighbor's patio. We're told Wes was also took a sledgehammer to a brick or cinder block wall -- which Wes thinks the neighbor put up on his side of the property line. Cops arrived...