"She just started telling everyone, 'Hey, $20 trees!' Selling them for way less than they're worth, you know," said Justin Mayfield.
The woman began selling trees even though she doesn't work at the lot. In all, she sold nine trees before she she fled.
"So all the trees she sold to whoever was coming by to buy a tree -- she pocketed the money and left," said customer Belinda.
Justin Mayfield opens this lot every year to raise money for a nonprofit organization he founded called Locallife.The group works to improve struggling neighborhoods.
"So it was sad to see someone would come and not only take advantage of what we were doing, but be so brazen, so bold about it," he said.
Some of Mayfield's customers think that's as low as someone can go.
"I think that's disgusting, I do. Isn't this for charity?" said customer Traci Hoenow.
The lot has security cameras, but they didn't capture the Grinch.
So the tree sellers will now move the security office trailer a lot closer to the tree, and never leave the lot unguarded or unattended.