The general consensus among experts is that a bicycle saddle should be level. If the nose is pointed up, it will put pressure on the perineum and cause discomfort.
If the saddle is positioned sloping downwards, this will throw too much weight onto your arms. Weight should be balanced between your seat and your hands.
But, how level? I feel to get out the carpenter’s level is over kill. If the saddle appears to be level to the naked eye, and it feels comfortable, to me that is level.
There are also so many differing designs of saddles. On my bike (above) I have a Concor saddle that was popular in the 1980s. Its design is swept up at the back and if I were to place a level from front to back it would indicate the saddle pointing downward, because the back part is higher.
However, visually the part where I sit is level. Unless the top of the saddle is flat front to back, it can’t be level at all points. Bottom line is how does it feel? If the saddle is not obviously up or down at first glance, I would say you’re okay.
This last part is for men only; so ladies you can stop reading now...
If you get that burning sensation in your scrotum, it is probably because the skin is pinched between the perineum and the saddle. If you reach down in your shorts and lift your boys up clear of the saddle; a proper pair of cycling shorts will hold them in place and this usually takes care of the problem.
Ladies, if you are still reading, don’t you do anything you are told?