"I am personally against exploiting mistakes (like apparently wrong priced offers, typing errors, etc. etc.).

I am all for getting the best official price, the best ratio of personal costs/rewards/services for me (and as many FT colleagues as possible)."

I agree with the above, but I am more apt to let the vender know when a genuine error has been advertised, not take advantage of it. I do this for two reasons: 1) I get something when I do so (tangible from them or a point in fairness) and 2) It is the right thing to do. When a vender makes a material error posting too high a price, it is likely to go unpurchased. All error therefore only cost them money. It is a one way road.

On point, a really good, but real benefit (Hilton point to update e-file, etc) is the kind of stuff that seems very fair and should be posted. If Hilton failed to put the limit on this benefit and someone up dated 10,000 times in a month (or maybe 3 times), that would surely be abusive in my book

Grocery store ventors and many other retailers are an exception. When the grocery store messes up and charges too much I make a stink until they get it changed in their computer. They have benefited by cheating people for ...(hours, days, ?) until it is corrected. It these people had to sell a couple items under the posted price (very rarely happens) it is purely pay back. Scanner are used to save costs associated with check out, and often for the generation of material gain as the expense of buy shoppers. But that is another topic.