I think Scout is likely yeah, but I think the Spy needs a lot more attention than the Scout does. The Scout may not have a very big place on DB or GR, but he's perfectly balanced on the rest of the maps.
The Spy however has a hard time whenever he's playing against a team of competent players. I can always tell a Spy from a mile off. It's just something that all the players have grown accustomed to spotting. See a guy with 3/4 health running in the wrong direction? Instant alarm bells. See a guy watching you/trying to avoid you? Alarm bells.
Now, I seem to get on fine when i'm a Spy. The key is to never ever reely on disguises. As i've said they're too easy to spot. I always cloak, wait, cloak, wait and so on until i'm where I want to be. The disguise is only there to stop sentries from killing me. But even when I go through all the effort of getting behind my target, which can take a very long time if I want to get there without dying, there are still far too many variables to make the class reliable. He needs work. The Scout gets on just dandy.
But yes I agree, its Spy or Scout next, but the Spy needs it more, and I think Valve know this.