This isn't relative pitch thing. An untrained ear generally can hear when one note is off by 5+ cents or so when playing a chord... when they're asked. And if

This isn't relative pitch thing. An untrained ear generally can hear when one note is off by 5+ cents or so when playing a chord... when they're asked. And if you're a musician, you will pick up on it very quickly in real time, in general. The key is most people will automatically filter it out until actually being asked unless it's egregiously bad. I would argue part of the issue comes down to guitar itself - 1) it's not a well tempered instrument. It's always kinda out of tune a bit 2) it can often go out of tune within the course of a song in live performances and 3) add some distortion on top, it kinda blurs things. So my take is people are just preconditioned to listen more to what is being played - in the context of a song - rather than whether it sounds a bit off or not. In short it's an attention thing, not an ability thing.