Obligatory "it's specifically the smell of bitter almonds and not everybody can smell it" reminder.

That said, if you're thorough and observant, you don't need to smell it to suspect its presence. For instance, because of the way cyanide interferes with cellular respiration, the hemoglobin in the blood tends to remain oxygenated, resulting in the livor mortis (from blood pooling in the dead body) taking on a cherry-red appearance. There are other things that can cause this (such as carbon monoxide poisoning), so be careful jumping to conclusions. Testing for cyanide is not part of the general post-mortem tox screening but it can be done on request.

And obviously, don't taste-test something you suspect to be cyanide.