"Go to pot" is a common expression that means "to get worse or deteriorate". "I watched my father's health go to pot after several strokes." "The moral climate of the world is going to pot."

to be damaged or spoilt because of a lack of care to become worse or be spoiled because of a lack of care for example My diet has gone to pot since the holidays.

to go to pot e.g. it went to pot - it's an idiom meaning some planned activity or event was a failure and pretty much everything went wrong.

This idiom was used in 1542, when the phrase first appeared, "to go to pot" was to be cut up like chunks of meat destined for the stew pot. Such a stew was usually the last stop for the remnants of a once substantial cut of meat or poultry, so "going to pot" made perfect sense as a metaphor for anything, from a national economy to a marriage, that had seen better days. Early uses of the metaphor were usually in the form "go to the pot." "Go to pot " is similar to other expressions like "go to rack and ruin" or "to go haywire" Other examples: Our picnic went to pot/ rack and ruin once the rain started. Things at the company went to pot/ went haywire/went to rack and ruin because the management was lazy.

Yes, this is a common expression that simply means that something is ruined. For example, my business "went to pot" when the economy worsened. This means that my business did so poorly that either I lost a lot of money (not much income) and/or I even lost my business completely. esl Larry also gave some great examples of how to use this expression.