On the last night of a 3 night stay, my code stopped working and I was locked out of my room. This was college graduation week in Boston, and the Celtics had a playoff game, so all of the hotels in the area were booked. I ended up homeless on a night with heavy rain. The host finally responded at around 5AM. I had an important family event the next day that I had to miss because it would have involved 5 hours of driving with very little sleep.
I also had difficulty checking-in. The host has a very similar property with a similar name on the same street only two blocks away. Google Maps sent me to this building and of course I was not able to enter. Although it was the designated check-in time, the host took around 50 minutes to respond to calls and emails for this issue.