I would agree....if you have a cold (or feel one coming on), pass on the dive. There will always be other days to dive, and they will be far more enjoyable. During my AOW class, I started feeling a bit under the weather (fine in the morning, but progressively worse throughout the day). Since it was a class I had paid for, I rationalized to myself that it would be okay....on the last dive of the day, I was pretty sure my head was simultaneously implode and explode. Luckily, someone's primary light died on our night dive and we had to call it early....no issues ascending, but definitely not an enjoyable dive.