I've written about the absolutely awful, cramped dark room that I got at a hotel in Barcelona, which I'm sure was due to booking on Hotwire. They were happy to charge me for an upgrade to a decent room the next day, and I was happy to pay it. Though I've since put this hotel on my block list. But I've also been upgraded and given really nice rooms too. For example, through Priceline once I booked The Intercontinental Park Lane (5* in Central London). I was given a 1 bedroom suite with a kitchen, separate dining room, living room, tons of closet space and an oversized bathroom on the top floor with a view of Hyde Park. It's hard to top that. So, it can go either way. I find that being extremely polite and friendly to the front desk staff at check-in is just as important in getting a good room as the amount that you pay per night.