"Good" restaurants can become terrible at the flip of a switch.

Usually happens at small local restaurants that get passed off to new owners who think some bean counting is the only thing thay they need to do become a millionaire, fully neglecting any real management and ruin the restaurant before customers fully catch on to the quality degradation.

First a dish is off, but you shrug it off... must have been a one off. Next the steak seems like a different cut, but it still tastes all right and they are running an awesome beer promo. The wife complains the fries are overcooked and cold, they are... but she is a slow eater and maybe it was just an cold plate. Next thing you know they are serving chicken tenders as thin as an I pad, tossed in Buffalo sauce as "boneless wings"