How about: Gee, nice coins. Do you always price them for the year 3008? What I do say: What is the non-tourist price?
OMG - Some of these are hilarious!! Ok, I've finally stopped laughing long enough to type and contribute some more although this is a turn from 'what not to say' to 'some of the funnier things I've heard': 1) Caller: 'can you tell me what my coin is worth? It's either a quarter or half dollar, I'm not sure and I can't find a date on it. Huh? Well, can't you at least guess?? 2) So platinum is about what.. $3000 today, right? 3) Caller: will you pay me as much for my coins as I can sell them for on Ebay? Why not? 4) What do mean this confederate money is fake? It's been in my family for years! 5) I don't understand - why would this $2.50 gold coin be worth more than that $5.00 gold coin?
Stuff a dealer should not say to a buyer! A month back at a show, some of us at a table were joking about the falling US dollar and the table owner said, "heck, its so bad, I'd pay $2 for every euro anyone gave me, but noone seems to have 'em here"... to which I produced a 10 Euro note from my pocket (I just happened to have one)... he grinned sheepishly and gave me $20 for it!
Or I have an entire roll of these blurry cents. Is there some way to get them to look normal? Will battery acid help?