It does my fuckin head in when some dozy bitch changes her mind.
On occasion after she has picked them up, loves them, can see perfectly but then meets a "chummie" who sticks the boot in.
The worst example was a mother and daughter "My daughter diznae like them"
The daughter then proceded to buy the same frame for herself THE SAME FUCKIN DAY.
Lenses in the bucket of course (at my expense)
Usually I swear a lot, throw things around, kick something, then come back through to the shop and refund the customer.
Most people of course are lovely but some would see you go out of business just to gain a fiver.