I couldn't not wash my cycling shorts. I have 5 pair, not including mtb shorts, knickers, or skorts, which I only wear on my errand runs or mtbiking. My tights are unpadded and I wear them for different things, along with cycling. They all go in the wash, regular cycle, front loader and hung to dry. Now that I have all "good" shorts, i.e. Terry Bella and Shebeest SSS, they show no sign of wear after a year. Once in awhile they go in the dryer, by accident, but I don't make it a habit.
With regular clothes I wear the most minimal thong I can. I don't wear them under pantyhose or tights, either. I hate the feeling of underwear in general!