Maybe they fixed it since I last checked, but I recall mp3ornot.com has some problems:
- the files are not level matched (the 320 kbps version is louder by a few tenths of a dB)
- it is possible to guess which file is which simply from the time it takes to load them (obviously, the larger 320 kbps version takes longer)
In any case, no one claims here that 128 kbps MP3 is transparent (or at least it only is with "easy" tracks).
It is only nit picking, but 3/3 (12.5% chance of random guessing) is generally not seen as a statistically significant result.