No hard and fast rule for me.
If I know someone is on a well, I would never do a load of laundry. I would (as I am this weekend) bring my own sheets and towels.
When we used to stay at my former mil's place, I would strip the bed, but leave the sheets roughly folded on the bed. I also folded up any blankets and stacked the pillows. She is fussy about laundry, it must be done her way.
Me, I do not use my dryer in the summer and my washing machine is finicky, I cannot fill the tub (old drain lines are partially clogged by roots and it is $$$ to have the lines replaced) , with out the water backing up during the drain cycle. If someone were to 'help' out by doing the laundry, my basement could be flooded and my electric bill higher than necessary. I would prefer to have the sheets, left in place and wash them and hang them on the line when it was convenient for me.
If I am staying with someone I do not know too well, I will ask if they want me to strip the bed. That does not happen very often right now.