Do snap locks change the action of baits in general in the water

Not sure of exactly which kind of hooks you are referring to, but if you are asking about using snaps (not snap swivels) instead of tying your lure direct to the line, that depends on what kind of lure and the situation you are using it in. I use snaps all the time on hard baits. Some other people prefer loops in their line....other prefer a direct tie.

I use Duo-Lock snaps, and I've never noticed any problems with lure action.

Falcon

I only use Duo-Locs for hard baits with treble hooks.  For everything else, I tie direct.  As far as the Duo-locs affecting the action, the answer is yes, as in yes the bait will run true more often than when using typical split rings.

I use crosslock snap for all my crankbaits.  Never have had a problem with the way they run.