When I was growing up and only had access to television reception via rabbit ears, the picture quality of the show wasn't all that great. But now that everything is digital and the pause button is at my command, subtle things that were barely noticeable before stand out like a sore thumb. Either by personal choice or by contract, the main actors apparently didn't do "dangerous" stunt work which reduces the credibility of the fight scenes. Observe...
So you think it was Shatner vs. Montalban in "Space Seed?"


The trademark Kirk drop-kick is there, but the Kirk-fu wasn't true Shatner style.
In "For The World Is Hollow And I Have Touched The Sky," Bones turns into a lean, mean fighting machine with a face made for battle:


"Shore Leave" had some serious Kirk-fu in it, complete with drop-kicks, double-first blows, and all kinds of other wild swings which are only seriously effective in the Star Trek world of the 1960s. However, one has to wonder during a distant camera shot who is really fighting Finnegan:

Everyone loves the classic "Amok Time." Friend against friend in a fight to the death. Kirk and Spock, human and Vulcan ... and two other mystery people. This is not Leonard Nimoy with the bowl haircut:


And that is certainly not Bill Shatner.
In "Mirror, Mirror," Spock determines that the entire landing party is suspect and attempts to interrogate them. However, a scuffle soon entails. Kirk eventually performs his patented double drop-kick on Spock. Except once again it doesn't look like Spock:

And that doesn't look like McCoy either:

The Enterprise visits Ardana in the third season episode "The Cloud Minders" where things gets tense and Kirk once again causes mayhem for the planet. Here we have Plasus and Kirk about to go hand-to-hand. Except, of course, that when Kirk puts on his true game face, his complexion changes entirely:

And in "The Savage Curtain," Kirk and Spock are once again forced to fight in order to survive and entertain aliens by using incredibly boring combat moves. For those distant shots, however, Shatner and Nimoy apparently decided a few bumps and bruises were not worth the trouble.

Over in the next century, Data goes machine-to-machine in "Descent." However ... this just doesn't look at all like the Data we know. Maybe it's that emotion being remotely pumped into him. Or maybe Brent Spiner didn't want to do simple stunt work in this scene:

Tap dancing is no doubt a skill with a steep learning curve. Just leave it to your stunt double wingman to do the heavy lifting when the time comes:

Data sure was the highlight of many an episode, eh? But for some shots, you just can't do screen-splits and have Mr. Spiner act in both places at once:
