I think it was XJW David Reed who gave the following illustration. Suppose an arsonist contacts people in a high rise and tells them that a serial killer is on the loose and that he's very clever. He sets off fire alarms to lure people out of their apartments so he can shoot them. If they don't come out when the alarm sounds, he pretends to be a fireman or policeman and orders them out of the building in order to lure them into his sights. When the fire starts, the authorities are shocked that no one heeds the fire alarms. When they pound on doors to try to get people out, no one opens the door. When they try to force the doors open, some tenants start shooting at them. When other tenants hear the shots, they become thoroughly convinced that everything they were told about the serial killer is true.
How does this parable relate to JWs?
Think of how often the WTS stresses the following:
1. In order to prove worthiness to Jehovah, you must overcome Satan's constant loyalty tests and endure to the end.
2. To doubt the WT organization is to doubt Jehovah God and side with Satan in the cosmic sovereignty battle.
3. Your entry to paradise may be only a few days away as long as you don't waver in your dedication to Jehovah's organization.
4. Satan will use all sorts of clever sounding arguments to get you to doubt the truth.
5. The only way to defeat him is to refuse to even listen to anything that might challenge your faith in Jehovah and his organization.
As long as a JW even thinks this MIGHT be true, he or she will ignore a lot of warning signs and suppress a lot of doubts.