1. Sandman is Uncle Ben.s killer. 

2. Sandman is directly connected to peter parker just like every villian so far has been. 

3. While im mentioning things being related to peter parker.

4. Flint Marko is turned into a sandman after falling in a hole where scientists are testing sand.

5. Every part of sandman turns into sand, except his locket. Why not? his belt turned into sand, thats metal. 

6. Sandman switches his personality at the drop of a dime. Alright he's not a killer, yet he kills cops.  

7. Sandman gets away at the end.

8. Sandman killed uncle ben. 

full list via broke-off