Product Quality: No, that’s not the same thing at all. “I love that shirt” just means that they like your shirt, not that they want one for themselves. The appropriate response is thanks, nothing more. “I love that shirt! Where did you get it?” means that they might want to purchase one, if not for themselves then as a gift for someone else. It’s up to you if you want to tell them. You don’t have to, nor do you need to give a reason. In this case, you might want to expand a little on the thanks, such as “Thanks, I like it too.”