let me put it this way...
A2/A3/A4/A5 that flops an Ace have no kicker. You're counting on no one else having an ace if one is flopped OR you're hoping for a wheel (which will always be an ignorant straight IE 345 flopped can be beaten by 67. 245 is beaten by 36. 235 is beaten by 46 and 234 is beaten by 56.) or flopping two 2s or 3s or 4s or 5s giving you trips with top kicker. There is a little value added by them being suited, but VERY little.
Consensus: Fold these untill you become short handed (5 people or less at the table), or Limp in late position. I generally even fold the suited ones.
Just for the sake of showing it... A6 only has a kicker if the board flops an ace by seeing A2234, A2235 or some variant thereof, and as such, its generaly the lowest kicker you can have, and you're almost certainly going to lose on the strength of your kicker (the best you'll do is split this pot, unless someone has their two pair counterfeited)
I hear alot about A8 being the cut off for calling because there are 6 cards below 8 (2,3,4,5,6,7) and only 5 cards above 8 (9,10,J,Q,K. Not counting Ace of course, since you we're talking about Ax here) Personally, i don't even like seeing A9 and sometimes A/To. I'll fold these in early position and fold to a raise in MP, and limp if there other callers in LP.