For us it would have been the Tides riviera maya:
A rubbish strewn dirt road up to it.
Light switches constantly not working.
Villa roof leaking.
Toilet overflowed spewing sewage into the bedroom.
A plunge pool /hammock and reading area that was un usable due to mosquitoes [they did spray for them but to little effect]
A noisy aircon that refused to cool the room below 80f.
Those are only some of the issues we had.
And yet on trip advisor,you'd swear it was heaven..
but then a lot of the "reviewers" lately have like one review.
If I need advice on something I usually ignore people with 4 or 5 reviews or less on there or I come here
We were offered 2 nights refund as compensation for the issues but surprise surprise... no sign of it yet after a number of weeks.