Suppose I raise pre and get called. Then the flop comes something like 9 10 Q with two hearts, and I have a pair of tens. Should I c-bet this kind of board with middle pair?
As someone mentioned earlier, it does kind of matter what type of player you're playing against. If Villain is really aggressive, I'd say no as he can raise a lot of draws or just simply better hands and you'll have no idea where you stand in the hand. But if Villain is really passive it might POSSIBLY be better to bet. Another important factor is if you're in position or not. If you're in position, betting might not be as bad as opposed to if you're out of position as you can pot control more in position than out. But, if you have straight blockers in your whole cards, such as JTs or T8s then it might be better to check as this reduces the amount of WORSE hands your opponent can call you with (i.e. straight draws). These are the kind of things you should think about if you're considering betting second pair. However, here is my advice to you:
Generally, I would check/call middle pair, especially if we have a straight draw to go with it (i.e. JT, T8). When we bet, we either want a better hand to fold or a worse hand to call. While there are many draws that are technically worse hands, many of them have a ton of
equity against you and can put you into tough spots on both the flop and the turn. As poker has gotten better over the years, people are realizing the importance of playing their draws aggressively. I can't tell you how many pots I've picked up by playing my flush draws, OESD and combo draws aggressively, and people have showed me strong top/middle pairs that they just fold on the flop or turn thinking that I most likely just have a strong hand. However, this is not always the case, and I think you can be exploited by a hand like 78 of hearts or AJ of hearts or pretty much any straight draw/flush draw that knows this is a scary board and a hand like a pair of tens can't call down multiple streets. Especially if you're OOP, betting middle pair on a board like this is asking to get exploited by a good player. Not to mention, you aren't going to get a 9 to call down multiple streets and you aren't likely getting a Q to fold to two, maybe even three barrels considering how the board runs out. So just good to keep that in mind.