[Pokerdemic]

Long time lurker, first time thread starter hear. I just recently got into poker and have been making my way through some of the books. I was reading Lee Jones's Winning Low Limit Hold Em at the bookstore tonight. On his section about the check raise, he has a footnote, where he claims that some people object that check raising, or sandbagging, is an unethical poker move. Does anyone know what he is talking about? Who are these people that consider check raising unethical? Where does this comment come from? I've never heard that check-raising could be unethical, and I am quite perplexed. Anyone have a clue?