Personally, even where I spot grammatical errors or occasional spelling errors (including using the wrong phonetically equal word e.g. their and there) I don't think badly of the writer. Sometimes, though, a writer doesn't make the minimal effort. Often you can look at what is written and tell it is not the author's first language. In which case "hats off to them" (well done) as they are better at English than I am in any other language.

Whilst writers should take more care, perhaps readers should also be more considerate.