Dottle is no big deal. Most toss it.
But, what blend you're smoking affects what the last bit of the dottle tastes like. Latakias and aromatics, usually taste the worst at the bottom. But, when I first joined this forum, there were many who were dottle savers. Lawrence was a mod back then and great all around guy, and he was the biggest proponent of dottle saving. Sherlock Holmes did this also, and JM Barrie (author of Peter Pan) writes about it in some of his short stories from the turn of the century.
Virginias and some burleys get "stoved" as you smoke them, meaning that all of the extra sugars get caramelized as you smoke them, making them tastier and sweeter. You just dump all of the ash, and plop the dottle into your hand and put it into a jar or silk slipper. It dries out some, and mixes with a few other dottles of similar blends, then you just repack that for a stronger, sweeter, tastier smoke.
Yeh, people gave them shit talk on here. It definitely wasn't an across the board acceptance, but what is on here? I've done it, but now I usually smoke all but a few bits and pieces, not worth drying out. But, Lawrence was a spearhead in that experiment, like John has been for water rinsing. Maybe someone else would like to experiment. It's not really about being frugal, as much as it is about just experimenting for flavor and exploration for exploration's sake.