When I was an elder way back...a person was consicered a doubter if they asked too many questions.We would pass the word through the rumor mill to be careful of so and so he / she may not be serious and may be placed in the congregation by Satan.
There wasn't any hard and fast rules that my congo used...just gave the person room to hang themselves then each pub would mark the person as they liked. No association outside Kingdom hall or FS.
That's my story
dan