In the second half of the TNG episode "Unification", Ambassador Spock is hanging out on Romulus teaching the Romulans about Vulcan culture. While attempting to find him, Captain Picard & Data both disguise themselves as Romulans, yet Spock does not. On multiple occasions, Spock is seen walking outside among Romulans without a second look, despite having no brow ridges. He's literally just a Vulcan dressed in Romulan clothing.
We should also consider another Romulan, Tallera, in the 2-part "Gambit" arc, who is
actually a Vulcan intelligence officer in disguise as a Romulan... and she has the brow ridges to complete her disguise.
I assume that Spock's lack of brow ridges was largely for actor Leonard Nimoy's comfort, but it has me wondering... are there any other TNG-era Romulans who lack brow ridges?
Note: I've ignored both T-Pel and Sela since there are obvious reasons they wouldn't have ridges.