I'm new to BOTL but have been smoking cigars for a long time. With the risk of sounding like a noob I have to ask, are you inhaling them? I have had many of the cigars mentioned in this thread but have never come even close to being sick. I do prefer a somewhat moderate smoke but the full bodied smokes mentioned here just taste harsher to me. I have always finished them and have felt fine. I do not inhale and wonder if those that have been knocked to their knees do. I have always been the lone smoker among friends so I have never heard of this.
No inhalation, some people have a greater tolerance for nicotine than others. If you're a dipper or cigarette smoker, you're probably not going to get any ill effects because you're regularly exposed to fairly high doses. If you dont employ other nicotine delivery systems, you probably just have a higher tolerance.
Personally, I'd not experienced any ill effects of nicotine from a cigar until I had one on an empty stomach and tired. It had me sweating and nauseous I felt like I had too much to drink, but I didn't even finish my beer. Dont recall the cigar, but it was with my father in law, and I had wife drive home because I felt like I was drunk.
I realized my mistake of the empty stomach and wont do it again. The cigar that kicked me pretty good despite having just finished a large diner was a Cain F. Had to really pace myself with that one.