some folks seem to think to get foundation properly pulled into comb that a hive should be level. in a feral setting (ie a bee hive in a tree) this somewhat ignores the fact that most trees sway significantly in any wind and therefore you would think that qualities like plumb and level are changing all the time. evidently ???? the bees know how to deal with some chaos in their lives.
I am a fairly traditional bee keeper with multiple/many/enough hives and sometimes trade offs just need to be made. some of my hives (now on pallets and often times uneven ground) tilt forward, some backward and some may even be level. as far as preference goes I would rather a hive tilt slight forward so that debris and water tends to run out the front door vs accumulation at the back side of my bottom boards.