Hamburgers make lousy leftovers...and other thoughts

Ever try to reheat a leftover burger the next day....it just doesn't work- the meat tastes like jerkied wild skunk...how can something so delicious change it's character in just a mere 24 hours...But hamburger in it's other forms can be absolutely delicious as leftovers.....for example

1) meatloaf- it can last for days and improves with age, eventually becoming a cold sandwich, smothered with ketchup

2) meatballs- also hold up to father time, and once I tire of them with pasta, will make for a great meatball parmigiana hero

3) Steak- ah burgers in their original form- a reheated steak isn't the best either, but slice it up and make a delicious open-face steak sandwich w/ melted blue cheese

So, why are leftover burgers so lousy and it's other forms so delicious???? Not that I ever plan on burgers being leftover, but sometimes it happens

oh...and leftover hot dogs are even worse, never able to regain their original grandeur