About 0.3% of the adult population is on registries in the US.

With 40,000 couch sales, there would be roughly 120 sex offenders would have bought that couch. You can see what I mean about the registries being bloated.

Doesn't really narrow things down until you add the brick factory, but then they already had it down to 40 houses.

But it's a mistake to even assume the couch was bought by the same house as the offender. The offender could just be visiting, or the couch could have been moved to a different house since purchase (sold second hand, or the owner moved). And you are assuming the offender had been caught before, or was even on the sex offender registry for abusing children.