Spider,
You are right about maduro wrappers. In the fermentation process, heat a moisture as well as longer fermentation time draw the sugars out of the leaf turning it a darker shade. This typically lends to them being tougher. However, what really makes them difficult to smoke sometimes is the moisture from the wrapper. Before tobaccco is rolled, the have to wet it to make it more plyable. Maduro requires extra moisture at this step. At this step is when the fermentation process starts again and a few days after rolling it will begin to smell like amonia. (side note: that is why a cigar is either best enjoyed right off the rolling table before the process starts or you need to wait at least 30 - 90 days before smoking to let the process finish) I am sure people have gotten a maduro from a factory box that has been excessively humidified, moldy, and smells this way. What happens is the cigar maker did not let them sit long enough after being rolled. Typically maduros must wait an addition 30 - 90 days before shipping. When people ask why there is such a shortage of Cusano 18 paired maduro or CAO MX2, consider that it uses two maduro wrappers which adds even more time. Just an interesting FAQ. Sorry for the rant.