Nobody wants to visit a website to be greeted by slow loading pages, broken links, and spelling mistakes. Google also views all these things as unfavourable, and as a result will punish your site by ranking it lower in searches, making it less and less likely that new customers will find you online.
Does your site display incorrectly on mobile devices? Is it difficult for people with disabilities to use?
Is your content out of date?
These common mistakes could all cause potential customers to leave your site – this is great news for your competitors, but how many lost opportunities does it mean for you?