Well, I don't take anything for granted and assume there is primer in everything, and tasting like you described. Before any of my precious juice goes into a carto or atty, all that can be boiled, are tossed into a gently rolling boil, filtered water for 5-10 minutes. Slung out, cartos dried using a baby syrup syringe, and then placed at my notebook hot air exhaust for a few hours. Attys slung and very careful dry burning if needed. With my thick juices, most that have to be cut with a little distilled water or PGA, they gunk up pretty fast especially the LRs.
I learned my lesson on dry burning cartos early on when I ruined a whole box of 801s dry burning after boiling them. I took one apart and sure nuff the wicking material that goes through the vertical burner had melted and fused with the stuffing, with a big burn spot in the stuffing.
The only way I know of doing a good cleaning on a carto, after use, is PGA soaking. When they start retaining a bit of burning taste I just chuck them.
E2's are a much better choice now that they've gotten most of the kinks out.
Alice