Tyrion either meets or glimpses him in A Dance with Dragons, it's been a while since I read the book.
So unless Gerion's appearance has changed greatly I doubt this is true.
I dont recall him ever coming into contact with him at all to be honest. Thats me though, you could very well be right.
I can think of tons of reason we can conclude he is not Gerion Lannister. First of which being he's dead and there is no evidence anywhere in the text that he is in fact alive as much as some of the passive-aggressive fan fic authors on this site may not like hearing it. So for this hypothesis to even reach theory stage you first have to prove Gerion Lannister is alive. Until you've proved that there is simply no way to prove any of your other assertions.
can you elaborate a few? and honestly, my point wasnt "what people think" but rather "evidence to support the fact he wouldnt be" sort of view. not to sound offensive, i mean none in the slightest. i can fully accept he isnt gerion lannister, im not formulating a theory or anything of the sort, not even a hypothesis. it's never mentioned he died, if i recall correctly. then again it's been so long, its minute that he'd be alive as well. however if he went into exile (like possible sandor/gravedigger theories), as well as became anonymous and beared no sigil (he wears tattered rags), no one would assume him lannister in essos
Not to argue against myself here but that doesn't prove anything. Gerion left for Valyria how long ago? At least 20 years and the only recollections Tyrion has of him were from when he was child. So Tyrion not recognizing him is inconclusive. That being said I still don't buy it.
Nothing to sell here, sir, there's nothing to buy. No debates, no nothing. Just looking for evidence that would disprove him being Gerion is all. He's described as an older gentleman with long white hair, blonde can always fade to white, he appears westerosi, in mannerisms and fighting style. to someone who doesnt know him too well, one would conclude the possibility, even remote. i simply ask for something that would confirm him not to be, or if there is in fact anything, that would.