If a phrase adheres to a certain rule, then I call it a Visionary Phrase™.
Use the examples below to find the rule.
In case you want it in CSV:
VISIONARY PHRASES, NOT VISIONARY PHRASES WHEN SOME WHIR, ONCE MANY PURR LUST THEN SNOG, SHAG OVER PINE SOME BOLD JAZZ, ANY OLD POP BREW NEAR OVEN, STEEP ABOVE STOVE MINER BURNT LOWRY, DIGGER SPOILT TURNER KILL HIS DATE, SLAY HER BEAU VOGUE TOFU CABAL, POSH VEGAN SECT FETAL RALPH WEEPS, BENT JOHN SOBS COTTON TIGHTS RUNOFF, SILKEN SHORTS SPILLAGE SAUCE OR GRITS, GRAVY AND QUESO OTTO PENS BLUE, JESS JOTS GREY BLUNT BAKER CLERK, CURT BUTCHER HELP PINK SWAN DON, GREY SHOE SUE THE WEAK PLED, FEW ABLE HID STEAM THREE BONES, BOIL FOUR LEGS
If you've been focusing on formal properties of these phrases, I would suggest shifting to something else; you can also try thinking along the lines of meanings and etymologies.
Focusing on the first letter should help.
Hints 2 and 3 are playfully ambiguous.
Focusing on 'A' should help. In particular, look for a pattern.