[simonh]

It's possible they're lying, that's true, but I think it's unlikely a secret like that could be kept long term. Employees have no reason to remain loyal when no longer employed by Apple and partner company employees would have to know about it too. The reputation damage would be catastrophic, so IMHO it seems unlikely they would take such a reckless risk.

So it's a matter of making a call between using vendors we know for a fact are tracking you, some of which have lied about it (see, hard to keep these things secret), or one that at least claims not to and has a lot to lose if caught out.