I've heard that. I haven't ever had them and can't speak personal from experience, but I've heard from a couple docs that cantharidin works really well, and cryotherapy ranges from might-work to total-garbage. Only downside is the whole "high potential for toxicity and misuse" thing; apparently people have taken cantharidin internally as a supposed aphrodisiac, which is clearly a terrible thing to do with a blistering agent.