A "perfect religion" is a non-sense idea. The fact that Jehovah's witnesses aren't "perfect" means they don't deliver the following expectations:
1. The things they say will happen do not actually transpire.
2. The qualities they claim are cultivated by the study of their publications do not develop at a greater rate than they otherwise do in the general public.
3. The effort to control one's behaviour, ideas and thoughts does not produce happiness. Rather, it produces the opposite of its intended consequences.
These imperfections serve as evidence which negates the claim that Jehovah's Witnesses teach true things. I have a lengthy philosophical argument which argues this, but here's the quick elevator version:
The governing body, if they were a channel of divine communication, would have to be perfect about information which came from Jehovah. God, were he to exist, would know exactly what he had to do to accurately convey information through a human channel. If he wanted people to have information, he would do so. This leads one to conclude either:
1. This God Jehovah does not exist.
2. This God may exist, but has nothing to do with the governing body.
3. This God may exist and may use the governing body, but is relatively unconcerned with the spread of true knowledge about him.
4. This God may exist and may use the governing body and is purposefully causing them to teach false things about him.
#3 is unlikely because it contradicts the theology in which the "governing body" exists. In other words, for #3 to be true, other things would have to be false which make the question pointless.
#4 Has been argued before, the most common version being a "testing defense." This has never held water for me. If you want to believe that God is testing your obedience to humans who he is purpusefully deceiving - enjoy.
That leaves us with #1 or #2. There are no other options.