If the compression for the 'not real SAP' is say <5% compression you could elect to remove the application definition from compression. Or I'd look at the flows to see if you can find the host that is serving this data....create a new application def maybe using the IP address of this server, place this new app above SAP in app def list by having a higher precedence for the new app and monitor this app....also find out what this app actually is....it may have application level compression in use (not encryption) as this would cause the application to get zero compression and you said it was low not zero.
Danny Jump Technical Marketing Manager - Access and Acceleration Business Unit
Since the customer won't give me an application definition for this 'supposed' SAP traffic, I decided to go with removing it for compression since the compression is very low anyway. My guess is there's an application level compression by default for that particular application.