9 times out of 10, if you look very closely at those plants, there's something wrong with them. If they've been infested, their "health" may be down. But more commonly you've missed some bit of pruning. One example.. on one variety the leaves kind of stack up on top of each other, and the only way to see some of the dead leaves that have live ones on top, is to move the clippers to "see" the very edge of the above leaf.. if you see the edge light up but not the whole leaf, there's a dead one underneath the live one that must be pruned. Another.. there's a vine where not only the little dead leaves but the dead stem they're on--which is almost invisible--must be pruned. I'm still working on the one out of ten that I can't figure out why they don't sell! Hey, maybe their bad parts are on the other side of the plant! <g>