One that I used to run into all the time by sellers of Canon out of the Philadelphia area was what we called the 3/5. The sales rep would write everything up from the proposal on emphasizing 36-months. 36-months was beat into the customers head like a drum all through the sales process. Everything was written as 36-months except for the term of the lease document which would be 60-months. The customer would get suckered into signing a 60-month lease thinking it was 36. Here's the kicker. The service contract really was 36-months. When the 36-month service contract reached its end the rep would come back and re-up the lease and roll the remaining 24-months into the new deal
If you were competing against them the customer would ask you to quote them a 36-month deal because that 36-month term had been beaten into their head by the Canon rep. Obviously if you quoted 36-months you'd be way high on the first go around and it might not even get caught on the second go around. Meanwhile the customer is rolling debt until they are completely upside down.
We ran into this over and over for a quite a few years.