You can block all updates from SFDC in the admin -> lead management, then select each field and click the "block field update" in gthe menu and check the "Salesforce" source.
There is not possibility to do that on the salesforce side, since the "read" right is required for the "create" and "edit" ones.
You can only do it for all records or none. You cannot select some records only.
BUT this is a good way to create problems.
Scenario :
- The person arrives on you site and fills out a form.
- She is pushed to SFDC.
- The sales update the data in SFDC, but it's not reflected in Marketo.
- The person comes back on the web site and sees her data in gthe form prefill, and decides to correct them, entering new data that differs from Marketo
- The person is updated in SFDC, which overrides the data entered by the sales...
- Additionnally, you do not know what happened from a Marketo standpoint, since you are blind.
Or what if the lead is converted into a contact and you do not know. The sync breaks.
Or the status is changed in SFDC and Marketo does not know. And yet, you should have stopped some campaigns.
-Greg