How off can a lime really be

“how off can a lime really be” a phrase commonly used in the United Kingdom that is used to explain that a bad situation cannot really be that’s bad

"let’s make some cocktails? the limes are old, but how off can a lime really be?"
"Is it safe to drink this pimms? It’s over a year old… fuck it how off can a lime really be"
"I want to buy this, but a buttons missing… but how off can a lime really be?"