@Bri_L I believe that someone who forms opinions about people based on their spelling and sentence structure and how much they respect them is saying more about themselves than the spelling and grammar of that individual ever could.
We form opinions based on all information at our disposal. The way someone dresses, their manner of speech, their attitude to others etc. If someone is scruffily dressed and wearing un-ironed or dirty clothes and shoes that are not clean and shined they will give a very different first impression to a person who is neat, clean, well mannered and polite. When your only impression is their written communication, it also creates an impression, it doesn’t matter how much you try to pretend that it doesn’t.
You don’t find carelessness in spelling to be of import – I do. And it is just carelessness, as anyone (unless the person has genuine learning difficulties) can spell if they make the effort. To me, those who don’t make the effort are lazy. I don’t respect lazy, although you can admire it if you wish. I do not expect or want you to be like me, I have no need to impress or make changes to others.
For your information, I also form opinions based on a person’s car – is it clean and well looked after (not is new or how expensive) or dirty, unwashed and full of junk. Also a big one for me is how their family treats them, you can learn a lot about someone from the attitudes of those close to them. I don’t like everyone – I DO not think that everyone is equal, and I prefer the company of people who I can respect.
There, now you have more ammunition. ;)