I use to work at a big box store, but I at least knew what I was talking about and if I didn't have an answer I didn't try to lie to them. I usually directed them here for more info. I have mixed feelings on interjecting though. I hated it when customers would interrupt me and give bad info and believe me it happened a lot "oh, don't listen to her you can totally put that goldfish in a bowl!" or "she has no idea what she's talking about, fish only grow the size of their home." However, I loved it when they would help out and back me up on an explanation of why filtration is needed or why you shouldn't mix certain species or answer a question about something that we didn't carry that I knew nothing about. Knowing this I try to stay out of it when I over hear something, unless the info is grossly damaging to the fish. Or if the customer is arguing with the employee over something like, really wanting to put inappropriate sized fish in a tank or mix things that will go drastically wrong. But I do always try to do it in a polite way. People listen better that way and the employee might learn something from the conversation rather than be offended. Usually, they're offended though. Such is life.