Arnold Palmer once was offended by a reporter who said he had a lucky round. His response was "yes, it seems the more I practice the luckier I get!".
Whether you are a mod or normal member, the longer you spend online the more likely you are to be 'first' in on a sale. There is no hidden window other than the modded posts already mentioned. If I were to want one of those items it would be approved first, then actioned in the same way as any other member. I can assure you that if a mod or admin were abusing their role in that way there would be a real barney about it between the admins and mods.
A fair question to ask, I'm sure others have wondered too.