I don’t do very much home renovating any more, but it’s a tough habit to kick. My senses still go into overdrive when I walk into an old house. I’ll surreptitiously run my fingers along cracks in the walls, pressing gently to feel whether the plaster’s still tight to the lath. I’ll slide a tentative foot into the corner of a room to determine how much the joists have settled. My eyes will be drawn to the joints in a hardwood floor, where the presence or absence of telltale nail heads will tell me if there’s one more refinishing pass in its future.

Of course, I don’t bring any of this up in casual conversation. Houses are like human bodies. It’s a good bet the owner is already aware of the flaws — sometimes, painfully so. People don’t really want to hear about them from strangers. Or even from friends.

Or, if they do, they want to hear the bad news from a professional, someone with a proposal for addressing the problem.

I usually leave well enough alone — unless, in my humble, un-asked-for opinion, there’s a safety issue, or a problem that has the potential to get a lot more expensive if it isn’t addressed promptly.

Case in point: a pair of charming — but crumbling — stained glass windows in the house where our daughter has cello lessons.

You couldn’t miss them: they flanked the front door. The arch of the doorway and the diamond-patterned Tudor-style windows were meant to suggest an English cottage, an architectural flourish popular in Baltimore in the Twenties and Thirties.

The metal window frames and the brass hardware were in decent shape, but the windows themselves were bulging as if they’d been punched from the inside. The lead caming — the thick black joinery connecting the diamond-shaped pieces of glass — was falling apart. Several of the glass pieces had pulled free of the caming and were hanging loose. Some of the gaps were nearly as wide as a pinkie.

I’m all for honoring hard-won signs of age in a house, but a broken window needs to be fixed, especially if it happens to be right next to the front door, at the height of the handset, and within easy reach of the deadbolt…

The cello teacher and his wife, who also gives music lessons, were in the process of converting their basement into a rehearsal space, a necessary but expensive project to accommodate both of their growing studios.

It was fairly obvious that their budget was stretched to the breaking point, but the miserable state of the windows was clearly a source of frustration and worry.

“I know, right?” the teacher said, when I asked if it was hard to keep the foyer warm in the winter. “It’s just, with the basement work and all…Say, you wouldn’t be interested in a, uh, barter, would you?”

As a matter of fact, I was.

We think of bartering as an ancient form of exchange, but it thrives to this day, especially in lean economic times, and in places where the hard currency has become unstable. People ask themselves, “Why should an hour of my labor drop in value, day after day, just because the drachma, or the deutschmark, is locked in an inflationary spiral?”

The Internet has enabled a new era of bartering, represented by websites like U-Exchange, and even Craigslist, where anyone can offer a good or service and seek a specific good or service in exchange.

There are even so-called “barter exchanges,” which function like banks — and are regulated by the federal government — only instead of holding dollars, they hold records of labor transactions. If you belong to one of these exchanges, you pay for other people’s services with equity you’ve built by selling your own. For example, I don’t pay you $300 for fixing my leaky roof; instead, I do $300 worth of car repairs for someone else. The roof repairer “withdraws” $300 worth of labor credit from the exchange; I “deposit” $300 worth of labor credit into the exchange. Neither one of us gets paid, but somehow both of us get paid. It’s beautiful, and utopian, and for millions of people, it works.

Of course, bartering does have its perils. I know, for example, exactly how much the cello teacher charges for a one-hour lesson. The market has determined his rate, and I’ve agreed to pay it. But how much are my window-repair services worth? What if I overvalue them? What if he undervalues them?

This is where trust enters the picture. The cello teacher and I have faith that we’ll figure it out in the end. He’ll examine the work, and together, we’ll agree on a fair price.

I like the honesty of bartering, the openness, the give-and-take. The cello teacher and I may not agree that an hour of window repair is as valuable as an hour of teaching — or vice versa! — but at least we each have a say. We approach our transaction, more or less, as equals.

I’d like to see the CEO of a big company stand face to face with one of his line workers and make the case, just as openly, that an hour of his time is worth a thousand hours of hard labor on the factory floor.

I understand the economics of it. This is Capitalism 101. But it’s still a pretty hard sell.