Mind you, I'm not a tradesman but still a freelance (I'm a surveyor, even though the actual job I do can't be described in englando).
When people come and pretend to know more than me, I usually charge more because I already know they're going to be a pain in the ass. Also they're the ones always asking for discounts and stuff.
Not the meme I was looking for (it was one with things like "if your buddy who "knows stuff" has looked at it first, $$$$ more), but it gets the point across
My favourite is putting architects and consultants in their place. Thankfully I've learnt the art of passive aggressive emails with a hint of sarcasm. Very handy for putting smart arses in their place.