Slang : A type of language that consists of words and phrases that are regarded as very informal, are more common in speech than writing, and...

One of our (already existed) categories; Translate This!: "Get help with translations of Russian words, phrases, songs and poems into English."
Another category is Grammar and Vocabulary: "Find answers to common grammar and vocabulary questions."
Which if you noticed, include a Sticky: http://masterrussian.net/f15/%D1%81%...C%D1%8B-14853/
That, kind of, include this.
Also this is not a new site/forum, it has been created since 2002, if it was such a big problem, we've already had a section/category for it.
I think you overrate this issue. The most important thing is that users learn and get the answer of their question. If we keep overrate such kind of issues, it will bring up a lot more categories.