One of the annoying phrases I’ve grown used to in India is, “I’m a guard, not a guide.” This is the start of a sales pitch by a security guard for tour guide services in the place he’s supposed to be guarding.
Actually, it’s not the start of the sales pitch. The usual opening is for the guard to just walk up to you, and without any request or agreement, start talking to you about the site or exhibits. Usually he’s not going to add anything that isn’t already written on signs and labels, and any information that does go beyond that is of questionable accuracy anyway. So you don’t want him to do this, since he’ll expect some kind of payment afterwards if you go along with it. It’s when you first tell him, no, you don’t want his information, that he assures you he’s a “guard, not a guide”. That’s when he’ll start haggling for the price of his guide services.
If you’re providing guide services, and expecting payment for it, you are a guide. And while you’re guiding, or touting for it, you’re clearly not being a very good guard, either.