I really dont use the rankings listed on TripAdvisor but believe the reviews and info is extremely valuable when making a decission on where to stay. I just look at the individual reviews and judge for myself who has valid complaints etc. I post a lot on TripAdvisor and find it the best site out there for getting info on a property. I think they are doing a better job these days of trying to make sure fake reviews are not posted but it is obviously difficult to police.
As far as Tripadvisor no longer being reliable. It has never been 100% reliable and never will be as it is end user generated content. Garbage in, garbage out. Nothing stopping someone from giving a 1 star review to a great hotel because they didnt take the mayo off their burger like they ask. Nothing stopping someone from giving a 1 start property 5 stars because they had indoor plumbing.
I just read the reviews and go from there. I have never agreed with their rankings and never really understood exactly how they derived them.