The Scandi is quite solid. Tbh, I have to thank the op for reminding me about this opening (for some reason I'd forgotten that it even existed!) You mostly get a better version of the Caro-Kann (as GM Larsen once rightly remarked). The reason it's not too popular has to do with chess fashion at the moment rather that it's objective strength.
I'll most definitely use it and post my results here! 
Here, finally. This one's against @Naroditsky-Bot (2650). I really wanted to play it live, but for some reason none of the sonnuva-guns want to play 1.e4 with me today! Anyway, here's the game:
https://www.chess.com/game/computer/8877007
I could go on with "so you see, the Scandinavian's not that bad"... but I just did so passive-aggressively by saying "I could go on with..." 
. Lol okay, that's just me being stupid. Ignore that. And yeah, btw, I really do think Scandi is really good (maybe even underrated).
I think a competent correspondence player could almost refute the Center Counter in both variations. By this i mean that he could find many lines where Black has an opening disadvantage quite a bit worse than he usually gets.
There was a time when I thought so too but when I found out IM Michael Melts played it regularly on ICCF and published a book on the Qd6 line, I realized I had to give more thought on my opinion. I think even if the scandi turnss out to be unsound, it is still something you have to take seriously. BTW Melt's IM title is in correspondence chess....just thought I should mention that to avoid confusion.
I played it I lost some games
mostly cause its a opening which gives white the feeling of "winning but stuck"
Back when I played e4, at least, I was annoyed because it violated the “don’t move your queen” principle and it wasn’t so easy to punish.
yeah exactly, white feels winning but doesnt know where to go from there
Well it considers the modern defense a mistake so I wouldn’t put too much thought into it.
it could be cause the engines are known for loving space control and initiative
From what I've heard, the Scandinavian isn't the best opening. But it looks fun, so I'll give it a try!
Melts got the ICCF IM title back in 1994, and stopped playing there 23 years ago. Which is the pre-engine era, and the games had plenty of mistakes.
And his book is useful only for archival purposes. Structurally, it is a horrible mess, and with a ton of analytical mistakes.
Current experience says that the 3...Qd6 line has some problems which are not easy to solve, while in the 3...Qa5 variation white is objectively better like that:
In a modern ICCF game, white is playing for two results in this position.
In OTB games, this is quite double-edged because white is "almost" overextended on the kingside, and this gives Black plenty of counterchances. While I do not doubt that white is better here, I would pick another, more practical solution to prove something.
Thanks for that. I didnt realize that about Melts. Also those kinds of positions with the bishops may be why the scandi is popular at below master level. At master level the bishop pair can seem like a totally winning advantage in the hands of a player with great endgame technique but it is rare to find a player with such skill at class level. What I am saying i that even if in the above position white manages to neutralize blacks counter play and get a simpler version of the bishop pair advantage, he may or may not know how to win it.
jamesstack wrote: Thanks for that. I didnt realize that about Melts. Also those kinds of positions with the bishops may be why the scandi is popular at below master level. At master level the bishop pair can seem like a totally winning advantage in the hands of a player with great endgame technique but it is rare to find a player with such skill at class level. What I am saying i that even if in the above position white manages to neutralize blacks counter play and get a simpler version of the bishop pair advantage, he may or may not know how to win it.
Similar can said about the Tarrasch Defense in that the IQP is not easy to exploit at club level. The Scandinavian and Tarrasch Defense are what I play. In the Scandinavian I use both 3...Qd8 and 3...Qa5.
play the Tennison Gambit
When I learned to play (in the 1980's) it was considered a beginner's mistake. When I came back to competitive play (around 2014) I was taken aback that it had become a valid opening. I still have trouble taking it seriously as a result.
I still don't think it's a valid opening honestly. I see the Scandinavian and immediately mentally prepare myself for a Bogo-Indian pawn structure (Nc3 d4 c4) and a queenside attack. If Nc3, Qd8 is the best move but it barely ever gets played, if Bogo-Indian pawn structure, White develops quickly and safely into a d4 structure with no real weaknesses, up a tempo, and there isn't c6/e6 d4 as a pawn break in the midgame. I noticed people explain that White won't be prepared, but if you play both e4 and d4, White will be just as (if not more) prepared than Black, and in a better position.
Because there isnt something easy to learn that deals with all three variations.
Maybe it reminds them of bad experiences with Ikea products.
I think it's because it's very unambitious, but there's no obvious attacking plan for white.
openings that blatantly violate certain opening principles, be it the scandinavian, or the orangutan opening or the bird variation of the ruy lopez or the mikenas, montevideo retreat, tend to elicit a big gut reaction in a certain number of the chess populace.
This attitude is often an advantage to those playing it, who know the opening/defense is better than it looks and and their opponent is bound to play with premature aggression or even cavalier dismissal.
Sometimes, even knowing an opening is ok is not sufficient to escape that psychological state. While i respect the Scandinavian as a defense if anyone would play the qd8 variation, i would have a hard time not feeling a strong itch to try and punish it, despite knowing its ok