The reason that you are getting a string of alphanumeric characters is that is the Salesforce record ID. The value in a lookup field in SFDC is actually the id of the connected record not the name. Salesforce in their UI converts the record id value into text when you load the page. To pull the right value through the connection you will want to have them create a formula field that takes the name of the parent object as opposed to the id.
Example: If I'm trying to get the name of the connected account from a case inside of SFDC, I would create a text formula that has account.name and then use that custom field to pull the correct text value into QB.
Hope this helps Ian