Looking at it visually I’m afraid there is no 100% sure way to tell. You can get a fair idea if you walk with your sniper laser aligner though. The V2 model can give you this but if you have access to the much more expensive V4 then that can tell you much more definitively as its designed to do just that…check chassis squareness.
I know most people don’t own the v4 though so I’ll go through a little procedure for getting a rough idea with the more common v2.
Basically you’re gonna do a proper alignment. Check the steering sweep first and foremost and ensure it is even left to right, then find true centre and set the wheel there. Next set both tie rods toe in/out to something easy to see…say one box toe out per side. Recheck the steering sweep. If it remains spot on it’s a good sign the chassis is straight.
Next set both the eccentric pills in the same physical position. Meaning, ensure that the pill on the right is set physically to the same position as the one on the left. Now look at the sniper. If the front end is 100% straight then the camber on either side should be spot on if not very very close.
Lastly you can check the caster with a metal ruler and a magnet. Set the ruler to stand vertically in the middle of the kart all the way to the front on the floor board. Sort of directly under the nasau panel. Next slowly turn the wheel left and right and take note of where the sniper cuts the ruler each side. If the chassis is straight on the front end then it will cut the same spot.
The last thing to look at is the amount of exposed threads on the tie rods adjacent to either rose joint. If the chassis is 100% straight after you’ve done all the above, the amount of threads exposes should be identical (once the tie rods or rose joints are themselves straight).
Once complete you can be fairly certain the front end at least of the kart is pretty straight. Without the v4 the last thing you can do to get a fair idea of the back with respect to the already confirmed front is to set the wheel back in the true centre position and then take a straight bar (must be 100% true) and put it on top the snipers. So the bar must be long enough to go the front width so it sits on top the snipers. Now go to the rear of the kart from a distance. Look at the gap made between the bottom of the bar and the top of your rear axle. This is just a rough eyeball test mind you. The gap should be parralel if the rear is straight with reference to the front.
Hope this helps you out.