Please, Sandra Lee makes millions of dollars doing this with angel food cakes! LOL
Although I've never done it with baked goods to date, I wouldn't rule it out in a pinch. If it was something really basic like some vanilla cupcakes, and perhaps I could frost them myself to make them look completely homemade, I would do it if I was in a hurry. There are some things that are so basic, like a pound cake, that really don't taste a whole lot different when you make them at home from scratch vs. getting them at the grocery store just after they were baked. I wouldn't try to pass off something like a store bought Kolachi as my own though. I think people would catch that in an instant.
Incidentally I have done this with non baked goods. I made a batch of pasta salad for a potluck at work the night before. But when I got up the next morning and tasted it a bit more, I really didn't care for how it came out. So I ran to the store and bought their own pasta salad and doctored it up with some more stuff like roasted red peppers and olives to make it look like I made it.