Yes, that mug stayed at my house. My big plastic water glasses, not so much. It wasn't that they were valuable, just that they were *mine*!
They borrowed so many things and took advantage of our generosity so many times that it would be a novel to write out. One time they tried to borrow a post hole digger but we didn't have one. I said, "You can buy or rent one from the hardware store for only $20 or $30." Instead, Mr. Snowflake introduced himself to another neighbor, that he had never spoken to once in five years and had to ask us what his name was, to ask to borrow his. Good times!
This reminds me of a story in _The First Four Years_, the story of Laura Ingalls Wilder's first four years (duh) of marriage to Almanzo. They are homesteading on the South Dakota prairie, and a neighbor is always borrowing from them and not returning items. Laura resents it, but Almanzo says they have to lend to him because that's being good neighbors.
One day Neighbor is butchering a hog. He comes over several times to borrow her washbasin, big scalding kettle, butcher knife, and whetstone. Laura thinks to herself that he'll be over next to borrow their hog!
In an essay written many years later (not part of the book, published in her local newspaper in Missouri), Laura goes on to say that the week after the hog butchering episode, she asked this neighbor to loan her the newspaper, and was told that they never loaned papers. But she says that in later times, this neighbor was very good to them at a time when they needed it.