I have a confession to make: I
enjoy spotting errors.
Okay, that's not strictly true. In published work, if I spot the odd mechanical error (useful phrase, Mere!), I get a perverse little thrill for knowing that I just got one over on the professionals.

I've never been unlucky enough to read a published book with lots of errors, so I've never reached the level of annoyance and/or disgust with these types of errors, although I suspect I probably would.
Here, I'm pretty much like Wendy. I spot a lot of mechanical errors which I just keep quiet about. I think the main purpose of these boards is to deliver feedback on characterisation, plot, story-telling technique, and so on, rather than the mechanicals. Perversely, I'm more likely to point out such errors if there's only one or two in a given section. More than that, and I'd use up all my feedback giving editing notes rather than critiquing content, so, as I said, I keep quiet.
I treat writers as I'd like to be treated myself - ie, I don't want my feedback hijacked by lots of typo and grammar corrections. The odd one here and there is fine, but leave the rest to my BR and/or GE, please.
Edit: I cannot *believe* I spelt 'grammar' with an 'e'! Yikes, how embarrassing!!!!
Yvonne