It seems agreed that charging a modest fee is the simplest and most fair thing to do. I don't think it matters if someone has left the house in perfect shape before. You simply declare a new rule. From this point on the fee is $X. For everyone, no matter what.
For the record, even if I had left the place in perfect condition prior to this, I would have absolutely no problem paying a small fee to use your cabin. Because I am a reasonable person, I would recognize that getting to stay there at all is a privilege and I would just be grateful I'm getting the chance. Anyone who would argue otherwise is basically just a jerk.