I can certainly attest to the fact that most JWs are indeed good-hearted, kind, and sincere individuals.
That is also my experience. However, when it comes to being kind to people that come to the KH, there is no doubt that more effort is put in the kindness for the objective of helping the person get a Bible study and eventually become a JW. This is done out of sincerity (at least that is how I did it) as most JW truly believe they are the only ones that will be saved, etc... for that reason you are normally shown just the good side and people are quite careful in trying to please you. I would compare this phase to courtship, you are shown the best side to be attracted. The dark side (even of single individuals) is usually discovered later (when you are already married and it is too late). it is just human nature, when we are selling something (even unconsciously) we work hard at it.
Wise words.Doing in-depth reseach into the Bible is very time consuming, and takes a lot of effort. Many people simply don't do this. It is easier to just study publications that tell them what to believe. This is where many people have been mislead by faulty Watchtower reasoning. I myself fell into this trap.
You'll need to do some research on your own. Don't just take our word for it. You need to be convinced yourself.