For the cruciblers out there;
Let's say you spawn at A on blind watch, enemy has C. Other members of your team go to B instead of trying to go to C to help flip spawns forcefully. You go towards C alone and notice only 1 other person on the other team guarding it. You kill him.
Now you are free to cap C and flip the spawn right? WRONG. THE FLAGS THAT YOU CAP HAVE NO BEARING ON WHERE YOU SPAWN. IT IS COMPLETELY DEPENDENT ON THE LOCATION OF TEAMMATES AND ENEMIES CURRENTLY ALIVE.
Once the other team notices their flag is being capped, they will swarm on you like flies on shit from B. You will die, and excommunicated back to A to repeat this process until you bang your head through a desk.
Instead, do this. After killing that lone ranger on C, hide somewhere near the spawn but not near the flag itself. On Blind Watch, this is in the far back behind the other door near where heavy ammo spawns at B. Crouch to mess up their radar. Going invis with bladedancer is even better. This will prevent their team from noticing you, and prevent the other team from spawning there when they die at B. Once you notice the other team has spawned at A, then you can capture C with no worry.
The direct counter to this is if you notice the other team rushing C, or notice one of your idiot teammates rushing A when you already have C, hide out near the spawn point at C and try to go unnoticed. Let them cap C even, just don't die and wait for your team to respawn at C.
This works very well on Blind Watch, reasonably well on Shores of Time, but mediocre on Firebase Delphi. These three are the most asymmetrical maps where it is imperative to control the good spawns.
TL, DR: Capping flags should be secondary to camping spawns to initiate the flip.
Last note: Yes, it's ok to capture the flag with the bad spawn. Just don't defend it.
Successfully spawn flipping the opposition is satisfying as hell. Having it done to you - like five times in a match - is rage inducing!