How do you know the flavor of the particular 'Every Flavour Bean' you were eating?

Question

In Philosopher's Stone, Dumbledore picks one of 'Bertie Bott's Every Flavour Beans' and claims "Earwax". And more humorous instances when characters had unpleasant flavors.

How did they know the exact flavor of the bean they were eating?

Answer 1

If I'm not mistaken, they were just guessing by the color. Also, they might have had a similar one before, so they could know from experience. Like red is strawberry, yellow is earwax.

Also, most people must have smelled earwax, so when they taste a earwax bean, the connection can't be that hard to make.

Wikia says

Τhere is also no way of telling for sure what flavor any given bean is without tasting it, although you can try and guess by the color.

Albus Dumbledore (Philosopher's Stone):

Ah! Bertie Bott's Every Flavour Beans! I was most unfortunate in my youth to come across a vomit-flavoured one. And since then, I'm afraid I've lost my liking for them. But I think I could be safe with a nice toffee... Hum! Alas! Earwax.

Addendum:

Ron said to Harry in The Philosopher's Stone:

You want to be careful with these. When they say every flavour, they mean every flavour - you know you get all the ordinary ones like chocolate and peppermint and marmalade, but then you can get spinach and liver and tripe. George reckons he had a bogey-flavoured one once.

George wasn't sure he got a bogey flavoured bean. So some of them could be just guessings

Answer 2

Dumbledore is a very, very old wizard. He had much experience throughout his life, and many chances to taste earwax. Even I have just scratched my ear and then eaten food a little bit later and tasted earwax.

I have also tried Bertie Bott's Every-Favour Beans (the candy shop in my town carried them for a limited time), and it was not hard to deduce which bean was which flavour. One of the first ones I ate was Vomit-flavoured; easily recognisable from the unpleasant taste and memories from having the flu as a child. There was also a Sausage-flavoured bean, and pretty much anyone who has had breakfast sausage any time in their life would recognise the bean as such.

Sometimes you can't be absolutely positive in which flavour you got, like when Ron was warning Harry about the beans and told him that George thinks he got a bogey (booger) flavoured bean once; once, as in he most likely has not had one since, either because he hasn't eaten a Bertie Bott's bean since or just hasn't stumbled across another one of that flavour.