My company does not use the Contact object in SFDC as a lead, so we're running into problems when someone who's already a Contact fills out a web form and gets synced from Marketo to SFDC - there's no place for their comments in a Contact, and I'm not allowed to change ownership of Contacts, and the owners so far just get confused if they get an alert email about one of their contacts.
I've thought of a few possible options for dealing with this, but convincing anyone else to change how they do things is a non-started, so I need options that I can enact as our Marketo admin.
If I changed the Marketo credentials so that it no longer has permissions to edit Contacts, would it start creating new lead records instead of syncing to the Contact? (this would work well for us, since duplicates are part of our process.)
What about if I changed the credentials so it can't see Contacts at all?
If there are contact fields for which you never want Marketo to push updates to SFDC then the best thing to do is to edit the Marketo sync user's profile and set the field level security for these fields to read only.
Think twice about it though, it may prevent good and more accurate information from reaching your sales team.