When you add sidespin with straight-stroke backhand english you don't stroke straight into it either - you angle your cue first. That's just like the angle you get by swiping.You swipe across it , not straight into it.
I have, many times. You have to test it yourself to see the proof, but it takes some patience and care - more than most here are willing to put up with.Prove them false then.
pj
chgo