The claim. Some antiperspirants say they won't leave white marks on clothes. Mitchum for Women Smart Solid Powder and Smart Solid Unscented (the men's version) claim "no white residue"; Degree Ultra Clear Pure Powder with Tri Clear claims to be "little black dress approved"; Dove Ultimate Clear Original Clean says it "stays on skin, not on clothes."

The check. We asked men and women to pit (sorry!) each of the above products against another one, from the same brand, that doesn't make the claim. Eight men tested the Mitchum unscented; 12 women tested the others. All the products were unidentifiable. Panelists applied a "no white marks" antiperspirant to one armpit and its opponent to the other armpit, donned a black T-shirt, exercised for about an hour, and reported the amount of white residue inside the shirts.

CR's take. Whether you're wearing a big black T-shirt or a little black dress, underarm yourself with Mitchum, which usually left no white marks. Degree left marks for 10 of 12 women; Dove did for 9 of 12. In each case, the nonclaiming product was slightly more likely to leave residue.