If marketing and sales have two different definitions of a good lead, the algorithm isn't your biggest problem. Campaigns will optimise for marketing's definition, and sales will report by theirs.
What's on the page
Fit criteria (who the customer is), intent criteria (which signal shows they're ready), exclusion criteria (who isn't a customer, however politely they fill in the form) and the statuses a lead moves through, with a definition of each.
How we use it
The definition goes into the form, as qualification questions; into the CRM, as statuses; and into reporting, as the difference between a lead and an opportunity. After a month, we compare again with what sales says — and adjust.