The sand in bunkers never seems to be the same. At some courses it’s nice and soft and at others it’s like gravel. The courses I frequent have bunker sand that they apparently ship in from rock quarries or something. The stuff is awful.
If you’re going to follow the letter of the law you can’t test the texture of the sand in the bunker before taking your shot. My circle of golfing friends isn’t quite that hardcore when it comes to our bunker shots so we like to give the ground a little tap with our club head first.
If the sand is especially hard in the bunker you’ll probably want to slow down your swing. Try not pulling back so far in your swing because the ball is going to come out much quicker without soft sand to cushion the impact. Soft sands requires you to take a faster swing. The light sand creates more resistance to the head of your club.