I'm a grown man and I still find myself wandering into the LEGO aisle of any given establishment.
On quite a few occasions, I've been approached by helpless adults with questions like, "I don't know what kind to get for my son/daughter/nephew/etc., how old is yours?"
They usually apologize profusely when I explain that I'm actually interested in them myself, and seem to feel as though they've just done the equivalent of slapping me in the face. It always makes me laugh, and I'm always glad to help regardless.
Most of the time they seem creeped out, but still take my suggestions.
I don't usually actually intend to buy anything, I just want to go look at it, especially if it's been more than a few months and I can be reasonably sure to see a new theme or at least a few new models. Sometimes I'll see something familiar, maybe an old-school model or maybe a resurrection of an old theme, or maybe something just vaguely resembling the results of one of the thousands of trips to the LEGO bin in my childhood.
If I'm waiting for someone else, someone who may be trying on sixty eight pairs of jeans, or shoes, I'll even pull them down off the shelves and read the boxes, like reading the back of a cereal box.
During one of these trips, I walked by a load of Harry Potter themed LEGO that consisted almost entirely of minifigs and very large, pre-formed chunks of scenery. I thought about a time when these vast (by LEGO standards) cave walls would not have been a vacuum formed monolith, but rather painstakingly constructed from hundreds of 1x1, 1x2, and 1x4 pieces, and likely would have featured some sort of laughably disguised secret passage.
I wrinkled my nose up in disgust, and another shopper, obviously much older than me, with a cart full of LEGO, said, "I know, right? But the grandkids still love 'em."
He noticed me eyeballing the contents of his cart and said, "For the grandkids. But, you know, when they aren't around I can play with them too."
I laughed and kept browsing while we talked about our favorite sets, most of them not in production anymore.
I guess finding a tub of old LEGO would be like finding your dad's stash of ancient porno mags - they're a little rough from use, the fashions are out of date, and you don't recognize any of the models, but there's still amusement to be had passing them around when your friends are over.