Oh, there definitely is such a thing as too much flux. I have some active flux that works really well on old and oxidized boards, but it's a pain to clean. I try to use only the amount necessary to do the job. No-clean flux still needs to be cleaned, but it's a lot easier to clean up, and with that I will say that I agree with your statement, conditionally. Having a swimming pool of flux or more flux than solder is not good.