1. The timeliness of reply or response between both ends: How prompt is the communication between the applicants and the whitelister. If a massage takes 3 to 5days before reply, it might lead to lost of interest by the applicants.
It varies from less than an hour up to a day.
2. How difficult or flexible are the questions: In some social media groups (Facebook especially) the questions are always simple and automated. Once you provide the right answers you are automatically in the group. Questions like; "Are you are buyer or a seller", "Will you abide by the rules of the group".
I don't ask questions, that would be too easy to give the answer I want to hear.
The people that can whitelist can develop some common and standard questions. Such that if an applicant decides to involve more than one whitelister, he/she will equally meets same questions.
Question: what happens when an account farmer answers all questions correct, four times per day?
Then there should be a common group by all the whitelisters were a general judgment can be passed on an applicant rather than discretionary judgment.
If you can come up with a better system, I'd love to hear it. But keep in mind the possibility of abuse.