Countering the left hand (the jab and in this case the left hook) is one of the most dangerous things to do in boxing. You are very vulnerable to the right hand during these counters and this is because the right hand can come instantly behind the jab/left hook and strike you as your body is committed to the process of countering.

Counter punching is inherently dangerous. This is something that is never brought up when people talk about countering but you have to be sure when you try to counter that your opponent isn't going to hit you during your counter. This is not something you can ever truly know for sure. You have to guess what he might do based on his his behavior and punch selection.

For example Howard Davis saw many lead left hooks thrown at him and concluded it would be safe to try and counter the left hook. The information Howard was working from caused him to think he would be safe from a right hand as he had no reason to believe he would get hit with one. This of course turned out to be very misleading. Courtesy of a one Buddy McGirt. If notice what Buddy did is very similar to the conversation I had with you a while back when I was talking about throwing my jab at you in hopes that I could trigger you into countering and catching you with my right hand.

Well ultimately countering (and boxing in general) has to do with being able to accurately predict your opponent's actions. I only like to counter when I can pull leads from my opponent and know with a good degree of certainty that he is just trying to knock me out with the lead and not set me up with the lead. I don't counter often and only if I believe I have a good feel for what my opponent is thinking.