If it's something you value or can't afford to replace, don't loan it.
I learned that lesson the hard way.
A friend borrowed my vacuum cleaner, which I had only used a few times.
It quit working on her, after having it and using it for a month, and she put it in her closet.
Instead of bringing it back to me, and telling me it broke, she kept mine put away and went out and bought herself a new one. Which is what she should have done in the first place.
And no, a messy house is no excuse.