in my opinion it's annoying. they should't appear instead word - for example my name chris [c h r i s]is a name of pirate emoticon, etc.
i think it'd be better if the 'normal emots' like , ;D etc. weren't change.
emoticons which replaces words, should be started and finished for example by < and > , or : ( like :chris:, or ) - they wouldn't be used by a mistake