There are three ways that salespeople work that cause false marketing qualified leads that I have yet to find a solution on, and I'm thinking Marketo could implement something to resolve each of these:
1. Updating industry on a lead - if a salesperson updates the industry on a lead and it triggers your lead scoring model for 'data value change' on the target industry campaign, it can push someone over the lead scoring threshold. I have tried to put into place a filter on this campaign that says 'not a member of this campaign', but that does not always work.
2. Merging two records together (in Marketo or Salesforce) - instead of taking the highest or lowest lead score, Marketo and Salesforce add the lead scores together. In many cases this creates false MQLs.
3. Cloning contacts in Salesforce - most salespeople clone contacts as part of an existing account to create new contacts. If the person they clone has points, and then they go through your demographic scoring campaigns as part of a 'new lead being created' this also creates false MQLs.
I think these are three instances where scoring can get modified when they really shouldn't be. Would be nice to see if Marketo could address each of them to avoid the unnecessary scores.