Are dogs masochistic by nature? My dog keeps on looking at me eat even though they know they won't get anything?

No.   But they are opportunists.   There's always hope!   To avoid that kind of possibility, we always fed ahead of our meal-times.

No, however dogs are forever optimists and opportunists

maybe your dog is hungry. Maybe buy him a plastic bone to keep him occupied and feed him good dog food.

Some dogs can be aggressive.