Accuracy, Underperformance in air rifles

[TCups]

What think you seasoned shooters out there about what acceptable accuracy is for springers and CO2 air rifles? I know that PCP will outperform springers and CO2 guns at longer distances, but what is your expectation of performance measured as CTC groups at 50 yards shooting off a rest with an air rifle that has been properly broken in, irrespective of FPE?  For me, I think anything under 1 inch is excellent, anything under 1.5 inches is good, anything under 2 inches is not great, but probably acceptable.  But anything more than 2 inches seems like there might well be a problem with the rifle or the shooter  or both.  

[RCnMo]

Anything shooting over 1.5" ctc at fifty yards disappoints me. I really like cloverleafs at 30yards, but it's rare for me. Pellets should go through a ragged hole at 15-20 yards in no wind. That's just what I like though.