I've been reading and posting on such threads for nearly 15 years and, unless I've been very inattentive, we've had very little feedback from people on this matter.
There certainly have been posts from several people who've said that they've got into the USA by simply 'forgetting' about their criminal conviction(s) though but there have also been just a few from people who've said that they (or someone they know) has been refused entry.
However if you (or someone you're thinking of travelling with) ar in a similar position now, you need to be aware of a recent change to the USA's attitude to people trying to sneak into their country.
Up until recently, it was not a specific criminal offence to try to gain admission to the USA without the relevant documentation (i.e. a viasa or an ESTA, as appropriate). So, if you were detected trying to break the rules, you could only be held in detention until such time as you could be placed on a flight back home (or, if you entered across a land border, simply sent back the way that you'd come).
However the Trump administration has now made it a criminal offence to illegally enter the USA (or to try to), resulting in some people (e.g. hikers accidentally straying across the border from Canada) being sent to prison for several months.
So the risks of trying to beat the system are now far greater than they used to be.