Are there any tricks to telling wether or not a bore is in decent condition? Is it as simple as looking down it, and if you see rifling it's ok, or is there something else I should be looking for?

Looking down the bore with a good light is the first best thing. You will be looking for of course pitting as well as frosting, dark or shiny (really does not matter on how they shoot). The real critical area is the throat, but that would require a bore scope which are expensive.

+1 on seeing what you can with a good light.

I've had some bores that look really bad, but I can still get 2" groups at 100 yards with them.  SO even though they look bad, I'm fine with the results I get.  I've got a Turkish Mauser that's like that.

Using a bore light after the bore has been cleaned and looking for what the other fellow said, any pitting large or micro pitting, any frosting or a haze look, and also how the condition of the rifling is.

I should add that a dark bore in no way indicates that it will be a poor shooter. Also if you hand load you can get a bore lapping kit and shoot out light frosting or darkness. I did this with a P-38 after about 50 rounds of various grit coated lead bullets.

Pitting also doesn't mean bad accuracy either. I had a 98k Mauser that had pitting. I cleaned the hell out of it and accuracy was just so-so. After a lot more shooting the groups tightened up. The copper fouling actually filled in the pits.
The most important thing I can think of to check is the crown. Most milsurp rifles have some damage to the crown from using cleaning rods. If it's bad but the rest of the rifle is good you can recrown it.
Other than that look with a good light. If the lands/grooves have a sharp edge and are shiny you are good to go.
There are some rifles that are counter-bored. There is no rifling in the last inch or so. Those had bad crowns and instead of vutting the barrel back they just counterbored the barrels back to good rifling. Those are usually as accurate as before the damage.

Jim

Looking at it is nice.

Shooting it is better.

Carefully slug the bore both ways, measurethe slugs, compare your readings to the ammo (bore diamiter and bullet diamiter).

Checking the Muzzle Wear and Throat Wear needs to be done with gauges. You can have a pristene looking bore but a rifle that will shoot basketball size groups with high Muzzle Wear. High Muzzle Wear will affect accuracy much. much more than high Throat Wear

My M44's bore looks really bad. There's no shine to it and it took a couple months of soaking in solvent to get a clean patch, but it shoots close to 1 MOA with S&B ammo.