I played him like a fine-tooth piano

This was heard on one of those cop shows on Court TV.  A woman who was helping set up a perpetrator uttered this one.  It is a mashup of “play (someone) like a fiddle” (easily mainpulate someone for one’s own needs) and “go over (something) with a fine-tooth comb” (scrutinize something).  The piano reference might be an eggcorn of ‘fine-tooth” for “fine-tuned”.  A “player piano” (mechanical piano) might also have been on the speaker’s mind.   A big thanks to Gary Kelly who heard this one and passed it on!