Deja,
I do a whole bunch of stuff in sorting my pellets, and washing them from the get go, gives me a clean slate to work from, right from the beginning. MOST pellets do not have a lot, if any crap on them, but every once in a while, there are particularly dirty batches, over all brands, some are worse than others. I only have one gun that likes Crosman Premiers, for instance. Wash those, and a full box yields as much as 10 grains of shavings and lead pieces. That can't be good for accuracy if you decide to leave it on there.
I include washing and lubing, just to illustrate how I sort and scrutinize my pellets from start to finish.
Tom Holland