I, too, have bad personal experiences with CO poisoning that make me a bit wary. A cabin full of fellow workers nearly died due to a malfunctioning pilot light. One woke up in the middle of the night with a splitting headache, realized the situation, and ventilated in time. Exceptional circumstances - a small, tightly sealed cabin - which are not representative of most homes.

I myself acquired a splitting headache after excavating an a closed space (which I thought was adequately ventilated) using a carbide lamp for ventilation.

If concerned, a CO detector (properly installed and maintained) provides an extra layer of safety.