The easiest way to determine if a cauliflower has gone wrong is to look for discoloration. The discoloration is usually the first sign of decay and can even be a warning sign of mold. However, identifying its smell and discoloration can tell if a cauliflower has gone wrong. The discoloration is also a warning sign of decay and should be removed immediately.
The warning sign of rotten Cauliflower is brown spots on the outer surface of the head. If the spots are visible early, you can just cut off the affected parts and discard the rest.