As an organisation, Vault-Tec is bad. Several of the examples of net positive vaults are only that way because the individuals assigned to those vaults purposefully disobeyed or sabotaged the intended purpose/experiment.

As for control vaults, ones which were always intended to function as advertised? Imagine this scenario - a company seeks test subjects for a new sugar alternative. Some groups are trying regular sugar, some a sugar alternative, other groups are actually having a variety of poisons tested out on them.

It’s not an exact parallel by any means, but does the fact that some people are not being poisoned in any way mitigate they harm that is deliberately being done?

Vault-Tec is definitely evil. It was never their plan to save people's lives, only to perform twisted social experiments on them. The control vaults and the vaults that didn't proceed with their experiments as they should have were the exception, not the rule.

Bad, bad, so bad

Vault-Tec tried to save the people in, what, seventeen Vaults? Out of over a hundred, the rest of which were tortured in some way? And even out of those seventeen all but one of the ones we know about (8, which grew into Vault City) failed, and in 0's case it failed because VT was cutting corners to save money. We learn in 76 that VT at least never intended to hand the rebuilt America over to the Enclave, but I highly doubt that they had absolutely no ulterior motives in doing so.

I do believe that VT started with good intentions, but they became corrupt by the time the Great War began.

In it for the money. I suppose that's the motive of basically every capitalist corporation. But they seem to have failed to realise that after a massive nuclear war, people will stop giving a damn about politics and money, because there won't be any governments or monies.