I am building a website in python/django and want to predict wether a user submission is valid or wether it is spam.

Users have an accept rate on their submissions, like this website has.

Users can moderate other users' submissions; and these moderations are later metamoderated by an admin.

Given this:

• user A with an submission accept rate of 60% submits something.
• user B moderates A's post as a valid submission. However, his moderations are often wrong, and his moderations' accept rate is a mere 30%.
• user C moderates A's post as spam. User C is usually right. His moderations' accept rate is 80%.

How can I predict the chance of A's post being spam?