DC seems to be entirely bereft of lead paint test kits,* so instead of using science, I put my powers of deduction to work.
The layers we scraped off our bathroom were as follows: top coat of off-white paint, almost certainly applied by Previous Owners in the 1999-2006 period. Then, wallpaper border, navy with teal and pinkish flowers in a kind of diamond pattern. Then, mauve/dusty pink paint which came off largely stuck to the wallpaper. Underneath that was a kind of greige paint which stayed in place, and below that were bright pink and teal paint layers which we only saw fleeting glimpses of through the greige.
I feel that the mauve paint must have gone up pretty much around the same time as the wallpaper border, both because they stuck together so much and because they coordinate. And (drum roll), the mauve/navy/teal scheme MUST be from the '80s. Yes? And thus must not contain lead, because only paint from before 1978 has lead. Yahhh! All the vacuuming and 3-bucket stuff was thus hopefully just an unnecessary lark.
*The Home Depot on Rhode Island Ave. said they never have them although people ask for them all the time (which, then, why don't they order some? but who am I to judge the wisdom of the Depot), and Logan Hardware says they usually have them but they don't now, or else they got some in on Monday but they can't find them, but they should get some more on Thursday. They were very nice about it, though.