Although the phrase "to be honest" (abbreviated "tbh") is often used in casual conversation, it is less usually used in published, edited material. It isn't in the lexicon because of this. Informal written communication is rife with acronyms, many of which are entirely unintelligible to those who are not familiar with them about what does tbh mean in text. However, these acronyms convey so much information so rapidly that, after introduction, the only thing standing in the way of acceptance is one's level of contempt for such shortcuts.