this is the truth. just about all fuel out there already has detergents in it - it's just not necessary. people will dump this crap in their fuel tanks and say it works, but the car was probably working fine to begin with. there's no quantitative evidence there. try to look some up, not much out there. the companies that make injector cleaners prefer it that way. compound that with the fact that the only way to test properly is to put well over 200k kms on injectors with no additional cleaners, flow test, run cleaner and test again. see the problem?
i'm not saying that injector cleaners can't do anything - just that its not necessary. go pull some injectors out of the oldest POS car in a junkyard that you can find. i'm willing to bet that they will still flow just fine.
my old car had well over 300k kms on it and never saw a drop of any kind of magic cleaning chemical in its life. still ran perfectly when i got rid of it. the key is that i maintained it well.
one final thought: the fuel you buy is required to conform to chemical standards to ensure that it does its job right without causing undue engine wear. these injector cleaners are not. do we know how they will affect seals and other components? how will they affect the cat? how will they chemically interact with the fuel itself? it's probably going to be just fine....probably. we also have no way to answer these questions. i'm not prepared to take that chance with my cars. if i need the injectors cleaned, i'll pull them and either set up a reverse flow rig or drop them in an ultrasonic bath.