totally agree....I had stinkers last summer!!! contaminates the whole incubator!
I find that the ring of death can appear by day 4, so I candle periodically every few days after that until day 10 to check for that, the quitters, and the infertile clear eggs. I also do a smell check at the vent of the incubator every day to make sure there's nothing rotting in there. You can smell it sometimes when an egg goes bad. I don't want any exploders!