If Australian authorities won't even share with an Australian employer that no conviction was recorded, then they are not going to share that with another country.
In any case, there are plenty of first hand stories (including here, quite recently) from people who DID have convictions (for assault, shoplifting, to name 2, both had convictions recorded but did not serve jail time), who lied, and had no hassles getting through US immigration. It appears we may share major convictions, and tyell you about really bad people you shouldn't let in, but we do not appear to tell the overly-anal US immigration service about the minor stuff even we don't care about.
FYI, by way of comparison, Australia only requires people with MAJOR convictions (defined as a jail term of 12 months) to disclose this when applying to enter. We couldn't give a stuff about petty crap you when you were a teenager.
