A woman of a certain age
If you compare spectrograms of properly extracted source audio that is properly encoded as FLAC against a high quality lossy file WITHOUT any filters then you will notice they are the exact same. I'm talking maybe a pixel difference here and there. You could screenshot both spectrograms, load them into Photoshop, and cancel out every pixel which is the same and you'd be able to visualize the (extremely rare) difference. This is an imperfect representation of an audio file, but it's the best we have and likely ever have. Imperfect as it may be, the proof is in the listening.
The greatest area of loss in a lossy file is in the extreme high and low frequencies as well as the stereo image. Kill all filters and you're left with the question of stereo image. Even MP3's joint stereo is great, but ogg's "point" stereo implementation is better. Comparing both, at high quality, yield few noticeable differences to the lossless source.
As always, it's about the way the tool is utilized, not so much about the tool itself. This has really always been the way it is, back to the days when you simply played loudly into a horn that caused a stylus to directly cut the wax. This has only become more true since entering the digital domain. Anyone who claims they can hear the difference between filterless CBR 320 mp3, VBR 224-320 mp3, CBR 500 ogg, FLAC/other lossless formats, and the lossless source is lying.