After 51 countries, hundreds of hotel nights, and countless check-ins and check-outs, I have easily encountered the very and absolute worst hotel experience...unfortunately in my very own country.
My check-in process included the "hotel" employee yelling at the guest who tried to complete her process and get a key, this same employee who tried, for 18 minutes (yes, I counted) to get me to pay her cash instead of paying with my credit card so she wouldn't have to pay the taxes, and finally threatening to add a $60 fee if I used my Mastercard.
The room had no heat. May I repeat, the room had zero heat, nor thermostat, nor heater. My attempts at contacting anyone from the hotel were unsuccessful (four times from four different people (including the Hotels.com employees).
I could go on and on but already, there is more than enough information for you the reader, to stay anywhere other than here.