There's been a long-standing process to have someone else proof read any content - or copy - before publishing. There's a good reason for this. Though you may have read and re-read your brochure or web page, your brain is very good at skpiping over the erorrs because that's just detail. After all, your brain knwos what you meant to wirte, so little spellnig mistakes are just distractions that can be flitered out.
Having a fresh pair of eyes removes the "I know what I meant to write" aspect of this process, thereby catching a higher proportion of mistakes. However, this technical process doesn't address the audience issue. Your web page should be designed to influence positively and attract a specific audience.
I recently reviewed a website which I determined was very old. There wasn't anything blindingly obvious that shouted "out of date", but the image of the vehicle caught my attention. With a number plate dating back to 1999 I started to question the validity of what I was reading.
With cheap "do it yourself" websites today it's all too easy for business owners to believe they're doing a perfectly good job with their website. But if the results raise questions in potential customers' minds like "is this company still in business?", or "if that's their level of attention to detail, then what are their services like?", then it would be better to stop all spending on the website... or better, hire a professional.