The real question here is how do we know it's a mistake.

I have legally stayed at hotels for $1 a night. With taxes and fees, I've paid $8.95 for the hotel for a weekend. The hotel was just fine with that.

Of course it's a little different in that I know that Priceline kicked in $20 bucks a night as a special bonus. Of course, I don't technically have to know that -- from my point of view, I paid $1 a night, or $4.50 a night including taxes/fees, for the hotel.

So what's not to say that if I see a $1 rate availably conventionally at another hotel, that it's not valid? Maybe the booking agency is kicking in some bucks as a promotion, just like Priceline did. Or I just don't care -- it says a $1, so it's a $1.

I'm not sure what side I am on in these sort of issues; I just don't think no mistake necessarily needs to be 'obvious'. I've paid a much as 95% off regular rates using various techniques -- when I tell people my rate, they don't believe me -- and the front desk does a double take (though they take it!) .. so I've had my share of 'unbelievably REAL' good deals.