Ok, so I'm not endorsing this, but i was curious......
I just went into my brewing room and took maybe half an ounce (it was the amount that fits in the bubble cap of a 3-piece airlock) of properly mixed star san solution (1 oz per 5 gallons) and added it to 8 oz of water and drank that. Didn't taste much of anything but water. Can't say if i would have been able to tell a difference in a blind side by side. Not saying I couldn't, but certainly don't have any confidence that I could.
Decided to really see what was up, refilled the bubble cap and just shot it straight. Pretty mild flavor, maybe like a very diluted, unsweetened lemonade?
I am not going to say for sure that you can't taste starsan in your beer, because hell, almost anything is possible. But I will say that I AM about 99% confident that you are not, in fact tasting star-san in your beer.