The "standard" spelling is
Scary-looking thing, isn't he?
I'm not entirely sure, but I believe this kind of spelling is called "eye dialect":
Eye dialect is the use of nonstandard spelling for speech to draw attention to pronunciation. The term was coined by George Philip Krapp to refer to the literary technique of using nonstandard spelling that implies a pronunciation of the given word that is actually standard, such as wimmin for women; the spelling indicates that the character's speech overall is dialectal, foreign, or uneducated. This form of nonstandard spelling differs from others in that a difference in spelling does not indicate a difference in pronunciation of a word. That is, it is dialect to the eye rather than to the ear. It suggests that a character "would use a vulgar pronunciation if there were one" and "is at the level of ignorance where one misspells in this fashion, hence mispronounces as well".
The term is less commonly also used to refer to pronunciation spellings, that is, spellings of words that indicate that they are pronounced in a nonstandard way. For example, an author might write dat as an attempt at accurate transcription of a nonstandard pronunciation of that. The rest of this article will discuss the former definition.
There's likely a technical point here I'm unaware of. Anyway, at the very least, the point of this spelling is to show that he speaks very differently from the others. I imagine it possibly reflects a real-world dialect, but I wouldn't know which one.