That would be for you to determine. You already admitted to yourself that you're not actually a fan in this particular example, so that resolves itself. But even then, one could still consider themselves a fan in those circumstances. One could just know or sincerely believe they would enjoy charcoal ice cream despite having never come in contact with it, or perhaps they have a more personal reason for liking charcoal ice cream. Maybe they just think the concept of charcoal ice cream is cool.
That probably sounds crazy, but it's not so different from fans of characters in Smash. How many people would say they are fans of characters like Captain Falcon, Roy, or even Geno, despite having only experienced them within the context of Smash? They've only experienced someone else's interpretation of that character, not the original character itself, so does mean they aren't allowed to call themselves fans of said character?
More to the point, what business do I have in saying whether you are or are not a fan? If someone came up to me and said they were a fan of charcoal ice cream despite never having it, who am I to say they aren't based on criteria I made up? Even if someone is lying about being a fan of charcoal ice cream, unless I already know they're lying, why should I tell them they aren't? I might as well dictate to someone what they like and don't like. It's not for me to decide.
This is why fandom scholars typically claim that fans are self-identified. The idea of a fan is so nebulous and broad, and the experience of fandom so personalized, that to allow someone else to determine for you whether you are or aren't a fan of something is... dumb.
And even more to the point, it's just really rude.
I can't really agree with this. I don't believe you can just say you are a fan of something and thus be a fan. The proof is in the pudding.
I can say I'm a can of Cheese Whiz or an Abominable Snowman, but as much as I say I am, I am clearly not. As much as some people hate it, this applies to more abstract things as well, like 'being a fan' of something. You cannot be a fan of something just because you like it. It's a bit more than that.
Merriam-Webster defines the word fan as 'an enthusiastic devotee (as of a sporting event or a performing art) usually as a spectator' and 'an ardent admirer or enthusiast (as of a celebrity or a pursuit)'. You'll notice something here, and that is terms like 'enthusiastic' or 'ardent', which can be connected zealous, fervent...or, what I like to call, 'OOMPH!' Being a fan means that you bring that 'OOMPH!' to whatever it is you like. You don't just say 'Yeah, I kinda like this show...I guess I'm a fan'; you would be more likely to say 'Dude, I am a HUGE fan of this show, we HAVE to watch this together. You won't BELIEVE how awesome it is!' There is a reason why the word fan spawns from fanatic...
Let me give you a better explanation in my own terms: investment.
Have you ever noticed that when you kind of like something you really couldn't care one way or they other about what happens, but when you are a FAN you occasionally go a bit to far with how you feel? That's the difference between something that matters and something that doesn't; that is the difference investment makes.
Take for example Game of Thrones. Someone who merely
likes GoT wouldn't care too much about Season 8 being garbage. 'Eh, they could have done better here or there I think, but it is what it is.' Does that sound like a fan to you? Or do all the videos and posts on social media going absolutely ballistic and picking apart all the issues and being upset at the writers sound like fans to you? Sure, they may have responded in ways you think were going too far, but they did that BECAUSE THEY WERE FANS. They didn't merely
like GoT: it was their favorite show that they talked about with their friends every day. They scheduled their time around watching the new episodes and even re-watching old ones. They named children after the characters. They bought merchandise and followed the cast on social media and...I think my point has been made.
To make this more personal, I found this mobile game recently. It's called Dungeon Tales or something like that. Discount Slay the Spires clone. I played it for a while for a day or two and mentioned it to a buddy of mine who likes deck building games, but I've already taken extended breaks from it to do other things. It's fun, and I
like it, but I wouldn't say I'm a Dungeon Tales fan.
...But SMRPG tho?
I mean, look where I am right now! I'm spending time on a forum talking with other people across the states and even the globe who love a singular character from a 23-yr-old game! I listen to the soundtrack frequently and I have a playlist I built dedicated to remixes after already having probably 15 of them in my Favorites on YT. I've livestreamed the game and I play it occasionally even when I don't truly own it but I want to buy a SNES Classic/Switch purely to be able to PLAY the game legitimately. Jesus, I HUM THE MUSIC AT WORK AND IN MY DAILY LIFE! If I could easily find merch I would buy it now that I'm employed (speaking of which, anyone have a link for the Geno Blast shirt from way back? I still want it) and one of my biggest wishes if for Geno to get in Smash, so big that if/when it happens I could actually never ask for anything more from Sakurai ever for the rest of my existence!
Yeah, there is a reason why there are phrases such as 'you aren't a true fan' and the like. Sure, you can be a fan in your own way and you can even be a fan of only a portion of something and not all of it, but you aren't a fan just because you declare it. It will show in your actions.