Short / Long answer type questions.
Why does sweetened milk taste bland soon after we have eaten sweets?

Once your brain becomes accustomed to a constant signal, it tends to ignore it and focuses on looking for major changes. So, if the brain is constantly tasting sweet, sweet things become the norm, and the brain doesn't notice lesser tastes much. Milk being less sweeter than the sweet itself is tastes bland as the brain cannot recognize the taste because it is not sweet.