Their is naught a spellchecker maid that wood correct this state meant.
MS Word would give you the green grammar underline, but we've all learned to ignore that as yet another Microsoft nuisance, right?
That's why we have brains.
As to the original point of the OP, I find that it is a rare website that does not include typos, misspellings, or bad grammar.
The same goes for crawls along the bottom of news broadcasts. Give me three minutes of crawl; I'll show you a typo. Typos are accidents, though, and we all make them occasionally; misspellings are a sign of the times and reflect on poor schooling and lack of professionalism.
Despite my signature, I'm quite used to seeing and ignoring poor spelling and grammar in internet forums and personal emails; it's quite another thing, though, if it's a business brochure or website. I would definitely think twice about paying someone to perform a service if they don't seek excellence in their own work.
Here's a worst-case scenario: I was once refused a job interview because in my cover letter, I claimed that "my design skills complement my technical abilities." After emailing the HR manager as a follow-up to a phone call, I received an email indicating that I was not considered for the position because I misspelled "compliment" in my cover letter.
One thing I will do to correct someone, though, is to email the publisher whenever I discover a typo or misspelling in a book I'm reading. Other than that, I rarely bother.