These people get one grouping, since I believe they have no idea what store they're in.
The Lost will confront you and demand to be shown to an item that you don't carry. After explaining that, "No ma'am/sir, we don't carry that." they will INSIST that they JUST bought one here, or buy the item in question here 'ALL THE TIME' and you just don't know what you're talking about. A typical conversation goes like this:
Lost - "S'cuse me, where's ya'll's PVC pipe?"
Me, politely - "Oh, I'm sorry we don't carry PVC pipe."
Lost, uppity tone - "Uh, yes you do, you just don't know where it is."
Me, frowning - "I promise we don't carry it. We've never to my knowledge carried PVC pipe."
Lost, pissy - "I buy PVC pipe here ALL THE TIME, I want to talk to a manager!"
Me, irked - "If you buy it here all the time then why don't you know where it is?"
A notable instance was when the laundry detergent of the world suddenly all switched to a 2x concentrated formula, and the normal one was discontinued- all the customers seemed baffled by this but a man actually shouted obscenities at me because it was apparently my fault he couldn't get Tide original 26 load anymore.
There are also the people purposely fucking with you. They know they didn't get whatever it is they want from the store they're standing in, but they're going to spaz out all over the place anyway.
I was actually vindicated once (only once) by the Lost's girlfriend who was quietly thumbing through a magazine while he shopped.
Lost - "Hey where's the Glade Glass Scents?" (little air freshener thingies like a jelly on a specimen sheet)
Me - "We haven't carried those in like, two years."
Lost suddenly FURIOUS - "What? Of couse you do, I buy them here all the time, I just bought one last week!"
Me (sighing) - "I don't see how that's possible unless it was a return from a different store and was accidently placed on the shelf instead of being taken to claims. We don't normally carry them, there isn't even a place for them on the shelf."
Lost starts working up a tirade - "I can't believe - "
Lost's girlfriend, glancing up from the magazine - "Don't lie, Jesus don't like it when you lie. You gonna go to hell for lying about something stupid like this?"
I stood, jaw agape, as they walked away. The rest of their conversation trailed off into - "Well, you gonna go to hell for havin' sex before you're married." "Well I guess you ain't gettin' any when we get home."
The Blind are these people -
They have looked ALL OVER THE STORE and can't find something that they are standing directly in front of. They come in all shapes and sizes and can react in various ways to being made to look like an asshole when you point out where something is.
Scene one - Nice person.
Blind- "Where's the tin foil? I have literally just walked all over this store and can't find it."
Me- "Right behind you."
Blind embarassed - "Oh, fuck I'm a moron, thanks."
Scene two - Jackass.
Blind- "Where's the fucking tin foil in this fucking store?"
Me- *slowly raises one hand and extends finger to point behind them while giving them a dead stare*
Blind- "..."
Scene three - The Dude.
Blind who has in fact been standing in the tin foil aisle for the past 10 minutes- "Man, where's the tin foil, I have looked like, everywhere."
Me - "Seriously?"
I can't even answer those people. I just walk away knowing it's going to be one of those nights.