I recently attempted to set up appointments with two ladies whose P411 accounts were temporarily suspended.  I also discussed this with a different provider and she indicated that this happened to her for not responding to Okay requests quickly?  Is this common?  What may cause a provider's account to be suspended?  Any concerns?  What about a client's account?  Finally, have guys been denied an Okay more than once?  What happens?  

The most likely cause would be a slow response to an ok request.

 
However, I think a provider (or a client) can get suspended from P411 for NCNS, if there is some proof.

 
My former ATF got suspended from P411 for a while, and she is no longer my ATF due to NCNS on two separate occasions with me. Several of her reviews in recent months mention her being late. Another local provider has been suspended from P411 lately, and it has happened to her before. Several of her reviews mention flaky behavior, and she got named on the local board two years ago for NCNS. In either case, it wouldn't surprise me if the suspension was for either slow response to an ok request or an NCNS.

on here is going to admit that they have been denied an okay from a provider. Im sure some may say they never received an ok when requested.

I'm not sure the answer of your other questions and I'm kind of curious. What I have been noticing is that some girls who are still active on 411 have links to TER yet TER states "provider information is no longer available on TER." It's unfortunate because this has happened to two of the girls I was planning to see. There reviews were good but no longer available to read.

In my area, a number of providers often complain about TER reviewers on Twitter. It wouldn't surprise me if some providers have decided to de-list from TER. But I remember how bad this hobby was before review sites, so I am no longer willing to see providers without reviews on TER.