Well, that should be the goal. However, the OP with sharp ears will always be able to tell if someone is using a bug even if their CW very closely mimics that of a keyer (which, again, should be the goal). Everyone makes mistakes, and your mistakes with a bug will often (usually?) sound different than your mistakes with a keyer or keyboard, just like they would with a straight key. As far as day-to-day operating goes, the experienced CW OP will usually be able to make an accurate guess as to whether the other OP is using a straight key, bug, keyer, or keyboard. They all sound different when one makes errors. BTW, just this morning I was trying to work a JA on 40m. He was having trouble hearing me so I slowed down to about 10 WPM and I struggle hard nowadays at that speed. I couldn't send my own call correctly to save my life. So he never got it right.