"Course, he always claimed to have emotions under check rather than wiped out."

Precisely. The few times in which he openly displayed his emotions were those in which they were so strong to be overwhelming. For example: his exuberance at discovering that Kirk was alive, instead of having been killed by Spock during ritual battle, in "Amok Time".

Spock was generally played as being profoundly controlled and reserved. It's not that he didn't possess emotions, but that they kept private and prevented from interfering.

The original series is somewhat inconsistent in this, though, as different writers saw things in different ways.