A fresh jalapeno is usually a deep, rich green color. If it's starting to turn brown or black, it might be on its way out - think of it like a brown leaf, it's just not as healthy as it used to be. Check the stem too - if it's dry and cracked, it's probably seen better days.
When you touch a fresh jalapeno, it should be slightly firm to the touch. If it's all squishy or soft, it's probably gone bad - kind of like when you squeeze a sponge and it just falls apart. And don't even get me started on the smell - if it smells like rotten eggs or something equally unpleasant, it's time to toss it.
How does one tell if a jalapeno is spicy? - Seasoned Advice
