Alright let's put some with what Vendel said earlier. I'll put "used to" in parenthesis because some of this still gets argued.
1. Cleriths (used to) claim that the high affection version of the Highwind scene wasn't romantic and the feelings shared could have been anything. But it was proven to be feelings of romantic love by "For the one that I love" and "Feelings of desire."
2. Cleriths (used to) claim that Cloud and Tifa wouldn't live together, but they are living together post FFVII and haven't moved away from each other since.
3. Cleriths (used to) claim Cloud wasn't happy with Tifa. This was disproved by 3 quotes that said he was happy with her and the kids.
4. Cleriths (used to) claim that Cait Sith's prediction was accurate. This was proven to be wrong by many sources saying his predictions were dubious, unreliable and nonsense. (Though this one might not be completely fair, there is SOME conflicting evidence about this)
5. Cleriths (used to) claim the koi Cloud saw on the way to see Aerith in the Forgotten City proved their love symbolically. This was proven false because it's not a koi
6. Cleriths (used to) claim that the ribbon Aerith wore in FFVII was different from the one Zack gave her which proved she was ready to move on. This was proven wrong by the Crisis Core keywords collection.
7. Cleriths (used to) claim that Aerith wore pink because she liked it. This was disproved by, once again, the Crisis Core keywords collection.
8. Cleriths (used to) claim that Cloud was himself on Disc 1 of the game. This was disproved with quotes that say he had created a new persona, and even though some of the original Cloud was there, he wasn't completely himself.
9. Cleriths (used to) claim that everyone in Japanese thought CxA were the intended couple. Obviously this is no longer true or perhaps was never true to begin with.
10. Cleriths (used to) claim that the relationship charts in the Ultimanias were proof that Cloud and Tifa weren't in a relationship. This was proven false by the many inaccuracies in the relationship charts such as Wakka and Lulu being listed as childhood friends and nothing more.
11. Cleriths (used to) claim that Cloud left Tifa and the kids because he was unhappy and missed Aerith. This was disproved by the many times we've been told it by the creators and HIM SELF that it was because he contacted Geostigma.
12. Cleriths (used to) claim that Cloud was the only one who could communicate with Aerith after her death. This was proven wrong in AC/C when she called the inhabitants of Midgar, including the adults.
13. Cleriths (used to) claim that Cloud being able to see Aerith was because her consciousness lived inside of him and this was special only to her and him. Again, proven wrong in ACC when he saw Zack (And okay maybe I'm taking some liberties with this one XD)
14. Cleriths (used to) claim Barret was in Cloud's family. This was disproved by the at least 3 quotes that say Cloud's family consists of Tifa, Marlene, Denzel and himself. And yes Marlene is Barret's adopted child but this does NOT automatically put him in Cloud's family
15. Cleriths (used to) claim, before AC actually came out that the line "I said I'd live out both our lives, easy to make that promise." was about Aerith. Disproved with AC, because it was about Zack.
16. Cleriths (used to) claim that Cloud only wanted forgiveness from Aerith. This was disproved by the Dissidia Ultimania (and other quotes I think) saying he wanted forgiveness from Zack as well.
17. Cleriths (used to) claim that Nojima saying "I don't intend to go into my views about love, marriage and family." was him saying he didn't want to get involved in the LTD. This is disproved by the fact that the question that preceded this answer was "Are CoB and CoT redemption stories." So he was not even prompted to talk about Cloud's love life and he did. Obviously Nojima has no trouble talking about it.
18. Cleriths (used to) claim Cloud was looking for Aerith in Kingdom Hearts. This was proven wrong by Kingdom Hearts Final Mix when it turned out he was looking for Sephiroth.
19. Cleriths (used to) claim that Aerith was Cloud's light. This was disproved by quote from Nomura (or was it Nojima?) that said "If Sephiroth is Cloud's darkness, Tifa is light." and obviously the fact that the creators wouldn't put Tifa in the story to just run around and fumble about looking for Cloud annoying him. AND Aerith even says Cloud will find his light. If she's his light, wouldn't she say "Hey you found me stupid" or something?
20. Cleriths (used to) claim that the promise Cloud made to Tifa isn't important to him. Despite Tifa strong arming him into it, this was disproved by the promise being engraved in his memories and by the fact that it's one of the three memories that make up the core of his inner being in the lifestream event.
okay phew, anyone else?