Sheet-style fabric softeners emit a wax-like substance that adheres to the fabric, making it feel softer and reducing static build-up. But, wax also reduces the fabric's ability to absorb moisture. Mrs. Gear insists on using softener sheets with the bath towels. True, the towels feel softer, but they don't absorb water as well after a shower. That...drives...me....nuts!!!!!!!!
But no harmthe stuff comes right off. Just re-wash any fabrics that were softened, and you'll be fine.
Overall, I've found that today's performance fabrics are extremely easy to care for. In olden days, for instance, one had to be cautious with polypropylene underwear, as the stuff would literally melt at a surprisingly low temperature. You'd toss an item into the clothes dryer, and a half-hour later take out a small compact ball of dark blue plastic. What a drag. But nowadays I toss everything in together, cotton and Coolmax alike, and dry it on the same temp. No problems.
But if I have any control over it, I DON'T use softening sheets.