The only tracks that are well produced and can pass on any Britney album are Work Bitch, Perfume, Brightest Morning Star, and Hold On Tight. Vocals aren't messed up and production doesn't sound cheap or anything.
ISBE is amazing, but the production is definitely very overused. Then there's Alien which is a masterpiece, but lots of fans complain about the vocal glitch (stupid complaint) so I suppose that should be taken into account, but if you aren't picky, then it definitely belongs as one of the songs that can fit on any other album.
But then there's Body Ache which is poorly produced and a bad S&S remake. WB was a good S&S remake. TTB is TERRIBLY produced, Passenger has horrid vocals and cheap production, and NTIFY is a WMU rip off.
Til It's Gone is outdated but it's good cuz I really like her vocals and the breakdown is kinda godly despite being repetitive.
Chillin With You and DC are both just there. Not terrible but just not much to do with them.
