I can't imagine having so many filter socks that using the washing machine isn't extremely wasteful.
That said 99% of the time I use the mesh socks, super easy to just rinse clean, hang up and the next day they are dry and go back into rotation. Every now and then I use felt ones when I would do some seriously deep cleaning that puts a crap ton (literally and figuratively) of detrtius into the water column. Those are a bigger pain, oxyclean works but I'm having a harder time finding unscented stuff (it all seems to have some level of flowery scent to it even if it doesn't say so on the box), otherwise I'd just use a spray nozzle and try to blow as much crud out of them as possible. 4inch ones are such a major pain in the butt that I tend to just not even use the felt ones anymore (well I haven't since I downgraded majorly)