That fine line between pedantry and accuracy

I've written before about the tensions inherent in teaching English at A Level: the seeming hypocrisy of not allowing students to describe such-and-such a dialect as "wrong" because it uses a non-standard subject-verb agreement (like "so I says to him,..."), while underlining their every mistake. Of course, a lot of that (or should that be alot of that? ;-)) is about context and mode - writing and speech are different, and have different rules.

This is one thing that I do really struggle with sometimes, and I really see myself fitting into that 'older person' stereotype of getting all hot and bothered about mistakes. I'd like to argue that it's about respect for words and grammar and so on, but just how school-teacherly and old-fashioned does that sound? I do see more and more misspelt printed and mass-produced material, and I do happen to think that is a problem. What intrigues me is the indignation people will display about this, when we all in fact make errors sometimes. I think, perhaps, we get all hot and bothered because we assume that someone making a mistake does so because they don't know how to get it right - but this may not be the case (although of course, sometimes it is). 

I was particularly amused at some students' disgust with Virgin Media when their 'superfast broadband' ads which mentioned each town by name misspelt Nuneaton as Nuneton. OK, this is a shocking mistake in a mass-produced billboard advert, but many of the students who were upset were the same ones who clearly think I am 'mean' or 'picky' to correct their misuse of  your/you're and bizarre (to me) constructions such as 'as a pose to' (as opposed to....).

For the time being, I am justified in correcting spelling, punctuation and grammar errors, since these things will cost marks in their A Level, although those marks are becoming fewer. I also think that universities and employers receiving these young people are likely to assume that an A Level in English (especially in Language or the combined Language and Literature) means they are able to write accurately.

How do you feel about accuracy in writing? If you find yourself uncertain about some of the more commonly confused homophones (your/you're; their/there/they're; it's/its etc) and/or apostrophe usage, you might find the  accuracy section of my student website useful.