yeah it does trap the resin, but when you think about it, most of the resin in the stem of your pipe doesn't effect the strength of your hit, because it isn't getting hot.. i'm talking the bottom of your stem, so your bowl still gets caked with resin.

i was just doing it because i'm sick and don't want to be inhaling a lot of shit into my lungs so i had to figure something out, but it makes for an extremely mellow, yet potent hit.