This is long, but well worth the read... it just happened to me.
As well as working at a tack shop, I work at a Fruits & Passion location. (It's a body shop type idea; think body lotion, etc)
Well, one of our products is a floating candle set. It's a glass vase and you get a few rocks to put at the bottom, some plastic foliage to make it look pretty, some water treatment so the water doesn't get gross, then you buy a candle and voila, a floating candle set.
Enter Stupid Woman stage right.
She comes right up to me at the counter and says "I'd like to return this set. It doesn't work. I set it all up and put the candle in and it fell to the bottom. No matter what I tried it would not stay at the top!"
I reply, in my sweetest sales associate voice ever, "Did you buy one of our floating candles? Regular candles won't work with this set; they need to be floating candles."
She is getting more agitated. "Yes, of course I bought your candles. I set it up and the candle just kept falling to the bottom!"
... Stupid Woman then takes a closer look at our display model.
Looks closer. Gets funny expression on her face.
You could almost SEE the lightbulb go off in her head.
She suddenly exclaims "OH! OH!!! You put WATER in it!?!"
Uh. Don't know what to say to that one.
Image of our floating candle set: