@Cassie118 Sorry you found yourself in a filthy place.
As Emiel said, it is the host who is responsible for saying they are doing this- hosts didn't have to sign up for it. And to tell you the truth, the majority of hosts who frequent this forum, who I know are all responsible hosts, decided not to sign up for that badge, because some of the requirements were ludicrous- like washing all the walls and the porch ceiling.
Now that doesn't mean those hosts who decided not to sign up aren't doing proper COVID cleaning- they are- they are doing the common sense things like leaving at least 24 hours between bookings, airing the place out, sterilizing all surfaces which get touched, removing extraneous items like a lot of throw pillows, etc.
I wouldn't look for that badge if I were a guest- most hosts who are taking this seriously have not necessarily signed up for that badge, but have added wording to their listing info as to what exactly they are doing COVID cleaning-wise. That's what I'd be looking for.