The observed pervasiveness of "oddball" JWs and JWs with clearly below average mental capacity was probably the very first troubling fact that I noticed about the cult - I remember asking my parents about this when I was about 12 years old: "Why does it seem that there are fewer smart people that have found the truth than ones like so-and-so." Of course I was given the expected nonsense about how god requires humility and he called those that were unlettered and ordinary, but even at that age I knew that was bullshit because "unlettered" was a status had by the vast majority in Jesus' time and besides other prominent figures like Paul and Moses were quite well educated, among other examples. The tone in my parent's voice and the look on their faces made it clear that this was not a question I should be asking, though, and the resumption of our family study shortly thereafter also seemed clearly connected. It didn't take me long to learn the lesson - suppress my doubts and any negative feelings about the cult or face consequences. That's a survival mechanism that's caused a ton of damage to my relationships and well being and I've only just begun to make progress resolving it in the last year or so.
Anyway, specific examples of oddball JWs:
The elder that did some of my baptism questions claimed to be anointed (and he claimed to be so before the removal of the 1935 doctrine, and he wasn't old enough to have qualified...) but most in the congregation couldn't see how he could possibly be anointed. During my baptism questions he went on a looooong rant about how his previous wife had cheated on him multiple times but he'd stuck by her because that's what jehovah wanted and it wasn't until she left him that they were divorced.
An MS of clearly diminished mental capacity once gave a prayer in which he apologized to Jehovah for "all the shit...errr...stuff that we do."
There were a number of MSes that clearly struggled to read, not just on the platform but in casual settings as well.
I knew at least 3 sisters that seemed to see god's hand in literally every aspect of their lives and weren't shy about sharing the details of these interventions in casual conversation as well as in 4-5 minute comments on an unrelated paragraph of the watchtower study. Experiences included deciding to go out in service instead of going to the store to buy toilet paper when, wouldn't you know it - she found a roll of toilet paper in the street.
Honestly, I think nearly all the eminently normal people I knew in the cult (or, at least, they would've been normal had they not been in the cult) were from the pre-1975 era when the cult literature at least had something that exercised the mind (even if said exercise was mental gymnastics) and the few exceptions to this rule were the children of these ones. It seems any new converts that came in after 1975 were all a bit loony....I guess they'd have to be.