No, the trash ones are the ones that have it good early on. The ones that survive hardship in youth usually end up being the good ones, as far as I can tell.
I think he meant that it would be trash in the sense it would be treated like garbage by its family. Surprisingly, the only one doing so turns out to be Reimu. Seems Reimus have a habit of doing this kind of thing.
It kinda makes sense... If Reimu are motherly and protective, it's only natural that they'd protect their children from garbage yukkuri. What we have here is a case of the Reimu not recognizing it's own child as a non-garbage yukkuri.
it's kind of ambiguous with yukkuris anyway? If they don't like the koyukkuri, it's always going to be borderline abuse or straight out abuse. There's very little I can remember that has simple "neglect" except for the shelled marisa series.