She-who-is-inspiring-my-baby-lust,
YES that is the biggest pain from the plywood floor. Obviously you've experienced this, eh.

I feel like a pioneer woman with a dirt floor! I spent a good half hour sweeping it yesterday only to have all the plys (or whatever that confounded texture is on it) catch all the dust and dirt and it stays exactly where it was in the first place. I mean, I swept with a broom. Then a little handheld broom with a dustpan so I could get up close and personal. Then I swiffered. Then I attempted to mop it and finally came to my senses (or the caffeine wore off) and said...well, something not so merry.
So yeah that drives me nuts. When he tore up the tile and subfloor under that, he also removed 2 layers of linoleum so the linoleum glue left huge craters in the plywood that serve as nice little catchalls for food and dirt and bits of crayon, etc.
(and, before you ask, yes we looked--and looked--for a decent floor under the 100 years of cumulative floors that are there and there's nothing, durn it)

GGB,
Stick with your son, sounds like he needs you more than ever right now.

later folks!