I've had no problems with these. Most of the time either the 'sandwich artist' (gimme a break!) or the cashier will do the upsell, if not both. If not, the sheet that you give them is still a positive spin on the situation so they still have 'next time' to look forward to. Their excitement at winning generally makes it worthwhile in an otherwise boring day.
I have found that they are sometimes reluctant to let me speak with the manager if they did not pass, and if that happens I just put on my non-angry 'this is business' face. I have had cashiers tell me they were the manager where I didn't believe it for a minute, but if they print their name as manager and sign the paperwork as manager, it is between them and the company to sort out what the heck they think they are doing.