The person picking up litter improves a view that somebody else will call untouched.

A place that looks after itself is almost always a place someone is looking after. The word untouched gets applied to the result of steady, unpaid attention: the bag carried out, the bottle lifted from the grass, the path kept clear. That work disappears into the very impression it creates, which is part of why it goes unthanked.

When something strikes you as naturally lovely, spend a moment guessing who maintains it. You can also join that invisible group cheaply by carrying out a little more than you brought in.