How do you tell if urine has gone bad?

I have some coyote urine from last year. I didn’t freeze it. It was left in an old cooler all spring, summer and fall. I think it smells like urine with just a hint of poop when I squirted it.

Do you think it is bad?

Not sure without taking a sniff BUT I have salvaged bad urine like that before by adding some skunk lure or IF you have some skunk essence to it.
It doesn't take much and while you lose your urine, you have gained a squirtable call lure. Try it.

You might get a digging reaction instead of a urinating response from it. I always say, when in doubt, throw it out.