At what rating does the Evans gambit fall off?

for online play it's decent. It becomes dubious when your opponents can prepare for you

#1
Evans Gambit is one of the sounder gambits, as it gambits a wing pawn and not a center pawn. It is playable at grandmaster level, but rather as a surprise weapon.
https://www.chessgames.com/perl/chessgame?gid=1018648 
You will not see it in a top level game anymore or in ICCF correspondence.

I don't think the Evans Gambit is dubious (perhaps a supercomputer can prove me wrong, but it isn't so simple). Certainly playable, and in fact something that I would recommend because not many people have a way of playing against it. 

Probably around expert level (2000+ USCF) I would suggest one to begin learning more solid lines as well (e.g. Giuoco Piano), but continue playing it if you like what you get from the opening.

Yea I feel like if you’re okay with the positions that come out after black uses their prep you can continue playing until master level with it (or higher??)

The Evans Gambit is not a "dubious" opening.  It is perfectly sound.  A World Champion is not likely to venture a dubious opening against another former World Champion...

Kasparov vs Anand EVANS GAMBIT...

https://www.youtube.com/watch?v=HsCAY5SxWwo

Introduction to The Italian Game & Evans Gambit...

https://www.chess.com/blog/RussBell/introduction-to-the-italian-game

Dubious reputation?  Perhaps someone should tell these patzers about that reputation:

Or these ones ...

If guys like Nakamura, Kasparov, Grischuk, Anand, MVL, Morozevich, etc can play it against their contemporaries, you can be pretty sure that it is not dubious.  If you let Stockfish 15 think about the position after 4. b4 for a while, it evaluates the position as roughly equal (in other words, it is saying White has compensation for the pawn).  Lc0 agrees with that assessment.  In terms of gambits, it is one of the, if not the, most sound gambit White can play.

Well, it was capt evans gambit...so what changed?

Did he run any slave ships? Well I guess that wouldnt matter, if any of the ships here used.

"In 1804, at the age of 14, Evans went to sea on a West India ship as apprentice"

Hmm..west india was a colonist powerhouse, and you would be executed for having anything to do with them.

The Naka game is a good example of how I feel about it... that it's a reasonable way to play for a draw as white.

Those were just a couple quick examples of it being used by 2700+ players against other 2700+ players in classical time controls.  It is often used by those same players in blitz and rapid with many decisive results.  Objectively, the computer holds a draw against it (just as it does for many openings), but humans are not computers.

I've seen other 2700s play stuff as white that I know is pretty crap... but when the opening's drawbacks are so obvious it's a good way to force your opponent into exploiting them... but since you're a 2700 player what you've actually done is just force your opponent into a draw because in spite of the opening's flaws it's still just an equal position.

For sure I've seen this with other openings, but it's just my opinion that the Evans gambit belongs in this category as well.

It's amazing to me that this "romantic" style opening is playable at the top level and even engines think it's okay. Maybe beauty in chess isn't dead after all!

I find myself playing the Giuoco piano gambit quite a bit, as black, and I used to struggle a lot with my opponents playing the Evan's gambit, until I stopped being lazy and actually started learning how to play against the Evan's gambit and not get completely creamed positionally. It's great against players who don't know the right lines, and still pretty good against players who do, I think...

#8
"If guys like Nakamura, Kasparov, Grischuk, Anand, MVL, Morozevich, etc can play it against their contemporaries, you can be pretty sure that it is not dubious."
++ Kasparov has played it twice as a surprise. In an interview he called it dubious.

Perfect

#16
The game against Short was an exhibition game, that does not count.
Just like the Fischer games against Fine (casual) and Celle (simul) do not count.
Precisely because Kasparov has played it twice and won twice in serious games he is credible when he said in an interview that the Evans is dubious.

RussBell
I study from your post about Vienna Gambit too.

Thank you very much.

Spassky and Bronstein in their time used to play the KGA successfully against top-level competition (and there haven't been many new theoretical innovations in the King's Gambit since the 60s and 70s), although it is well-known that black has many adequate lines to achieve easy equality. The problem for their opponents (including Fischer) was that at the board it was possible to play only one of them!

Similarly, the argument that the Evan's is 100% sound just because world-class players have (also very rarely) used it against players of the same level is not quite convincing. 

My (objective) opinion is this - If the opponent is prepared for it (ie. they know the good ol' Lasker defense), then there is no point in trying to play for an advantage after the first 6 or 7 moves as white, against equal opposition. Otherwise, it can promise powerful attacking positions with pretty miniature wins in store for you if you're lucky. So it becomes a particularly effective as a surprise weapon [at all levels], but I wouldn't recommend making it your main Italian Game repertoire.

Of course, all this is for serious otb chess competitions. On the internet, there is no pressure whatsoever and the main point is to have loads and loads of fun playing chess

I think if the opponent is prepared as weel as you it has chances for both

Not really. If I'm playing the regular Italian with 4.d3 etc. then with equal preparation the resulting positions will be one with chances for both just like you said.

But here we're talking about one specific opening which relies upto 40% on surprise value, because with equal preparation, the Evans' positions are always =/+.