Normally, someone who has sold tickets more than occasionally knows to crop that stuff out on a screenshot. With that being said, unless the venue, show, etc. is only selling SafeTix that have a dynamic or rotating barcode, the screenshots should be valid. The QR code is the exact same QR code that was originally generated for the ticket. Now there is never a 100% guarantee that some ticket taker will decide that he/she wants to make a scene but as a general rule you will be fine. Tens of thousands of these screenshot tickets have been sold on StubHub the past several years with no problems. StubHub has a Fan Protect Guarantee in case something unexpected happens.