I've never had it either. And it's hit right away, the plugs, not the clones themselves. I try and mist them once a day, keep the tray very low, not a real moist environment, just perfect is where I think I'm hitting. My success rate is 99% lately, if I lose one it's cuz I did something stupid to it or the mother wasn't ready/healthy. Do you think the lil solo cups with perlite would work, cuz I sure do. The clone/mold things frusterating because I'm normally solid with cloning and it's pretty fundamental. I suspect the rapid rooters, and the store I got them from. I have to try something new though because I gave to get good clones off the purplewrecks, the mamas aren't looking so hot and I need to snip in ~2 weeks.
Yea solo's with just perlite should work great for cloning. I've never used it myself, but i've seen it used with great success