constant critic

• nitpickerOne who criticizes trivial details
• faultfinderOne who criticizes constantly
• nagPester repeatedly
• cynicDoubter of good intentions
• skepticOne who doubts claims

harsh · judgmental · relentless · unforgiving · perfectionist · carping · scolding · disapproval · scrutiny · pedant · curmudgeon · grouch · killjoy · complainer · heckler · snide · cutting · barbed

• criticscritic, critics, criticizer, criticizers, faultfinder
• grumpsgrouch, grump, curmudgeon, sourpuss, crank