I get embaressed sometimes a lil annoyed when I see, I say salaam to every Muslim when am outside but some they don't return it.
I feel obliged to, as our nabi sallahu alayhi wasalaam made it sunnah to give salaams and if you don't the angels are shocked that you walked past a Muslim.
However for those who get no return in Salaam, don't worry because a friend told me the Angels return your salaam.
Alhamdulilah I felt so happy when she told me!

Wasalaam