Based on what I've seen, hosts are more dependent on good reviews. Guests, not so much. When Guests get bad reviews I've heard they tend to delete their account and register with a new e-mail and start fresh. For hosts, this is much more difficult as we have set up listings with our accounts.
Hosts need good (5 star) reviews from guests to become super hosts, and when reviews are not 5-star hosts recieve threatening emails and notifications from Airbnb that we are "not meeting Airbnb hosting standards" and that our "account could be suspended" if we don't improve ratings.
From what I know, guests face no direct penalties from Airbnb for having a bad review from hosts. It's just that hosts might be reluctant to host guests with a bad review from a fellow host.