Depends what you mean?

Yes, if someone makes a simple typo, such as writing "wahtever", it might be considered rude to point that out. ;)

On the other hand, if by how another "spells", people are referring to txt spk, then in my opinion, it is a problem with regards communication. txt spk may be necessary on a mobile phone with a very small screen and where you have a character limit, so it's often necessary to abbreviate words.

I see a lot of txt spk on internet forums and it's not necessary and, to me at least, and to others, it's a problem.

There's no need to abbreviate so coarsely on an internet forum. You're very unlikely to run into a character limit for most posts, so why feel the need?

Also, given that the population of these boards is multinational, but the language of communication is -- for the most part -- English, with the odd smattering of Arabic, French, filipino or urdu or malay or whatever languages those other posts are in that I can't read, then I think it's not rude to point out that a person is failing to communicate effectively by their use of bizarre spelling, but in fact, they are the rude ones.

Using slang and txt speak is very exclusive, it excludes people who don't understand it.

What about all those people for whom English is a second, third even fourth language? They take the time and effort to learn and utilise an 'international' language, and in response people subvert the use of English, use silly txt spk and unusual slang... I consider *that* to be rude, it's a bit of a slap in the face really.

Maybe it's just me, but when people are making an effort to use a common language, (and for some people, it is a big effort, which is very much appreciated on my part) you should have the courtesy to communicate in that common language instead of writing nonsense in txt spk. It's just plain rude.