Obviously, it’s a personal call. If it was a fairly small local business that did the work, and I like them and the work they did, then yes, I would believe it would be ethical to inform them. If it was a big ol’ corporation with shoddy financial management, then no, probably not, but I would endeavor to find out if it was a locally owned franchise (then yes, I would) or just one of a corporately owned chain (then no, I probably wouldn’t).