Mark,
The remarks about your site were unnecessarily crudely expressed, which is a shame. However, there is a glimmer of sense in them. I've posted on this topic before here, as it's one which does upset me, a pedant in correct use of English.
I see web sites with spelling and grammatical mistakes all the time. Mostly, I just sigh and ignore them. But if that site is trying to sell me a product, whatever it may be, that requires care and skill to get right, and with which I shall be unhappy if it's not right, I can think of only two reactions to such errors.
One is that the chap running the site is so good, and hence so busy, that he just doesn't have time to care about the state of the site. Will I use him? Maybe, but with reservations.
The other is that he just doesn't care about detail, and that the sloppy site reflects his approach to his work in general. Will I use him? Not a chance.
It's like a job application. Each year, colleagues of mine (happily, not me, at least not yet) have to sift through hundreds of applications to join us. Those with poorly-drafted covering letters just go straight into the bin. Presentation matters. Grammar, punctuation (which on your site is pretty bad, I'm afraid), spelling and the like do matter. You may think that's unfair, or wrong, but it's true nevertheless.
Jeremy