It was disappointing to get a marketing e-mail from Xcel Energy with the subject line “Alexa, give me a great deal,” as even the trusted power company appeared eager to get a sophisticated surveillance device into our house.

Alexa, of course, is the artificially intelligent voice that responds when consumers want to talk to a machine sold by, maybe to place an order for more stuff from Amazon. It turns out Xcel wasn’t selling an Amazon device, just a fancy version of a home thermostat that uses the Alexa voice recognition system.

Having a machine you can shout at to turn up the heat seems a little silly but harmless enough, yet this ecobee4 model that Xcel’s online store had pitched also promised to let owners ask for the news to be read aloud.

So really how smart — and harmless — is one of these things?

An actual Amazon Echo device, and the similar products produced by the likes of Alphabet Inc.’s Google business, promise far more capability than a smart thermostat. The popular Echo Dot looks a little like a hockey puck with a power cable, a hockey puck you can tell to ship some paper towels.

What is becoming obvious is that Americans find digital home assistants pretty cool, but it must be only because they do not think too much about how much data is being collected by the big companies that sell them.

When asked to think about it, they don’t much like the data collection that is going on.

A recent quick survey pointed out just how much consumers are of two minds about their technology. More than two-thirds of respondents, as reported by the online publication Axios, said technology had a “positive or somewhat positive” effect on us. Yet in that same survey more than three-quarters thought it was a “bad thing” that the big technology companies collect so much information on us.

For me, at least, a device like an Echo is a daily reminder that these big companies sure do seem to be in a position to learn a lot about us.

Just by listening, an Echo will happily add paper towels to an order underway at Amazon. It is also listening in on the household’s comings and goings. It can be taught when it is time for the kids to be called to dinner. Apparently it can remind parents to make sure the kids have their boots if the forecast calls for snow.

With past purchases, shopping habits, and now with an Echo listening for the daily habits in the household, what more useful information could Amazon really want?

As cool as it sounds to order cat food while strolling through the kitchen, buying an Amazon Echo for the kitchen counter seems to be an agreement to share the house with Amazon.

It would be a little like parents deciding it would have been a good idea to buy a baby monitor from the KGB.

Maybe a third of American households now have at least one digital home device like an Echo, based on a rough estimate by the partners of the Minneapolis venture firm Loup Ventures, who track such things carefully. Managing partner Andrew Murphy called this no more than a refined guess, but it is based on the solid estimate that maybe half of American households have an Amazon Prime membership, Amazon’s form of a buyer’s club.

“Keep in mind, you can now get an Echo Dot for the price of a tank of gas,” Murphy added. “And Amazon has been pushing them hard for a few years now.”

It is difficult to imagine that any Amazon executives are worried about whether Amazon turns a profit selling a Dot. It is playing a far longer game, looking to build value from its ever increasing store of information on its customers, their tastes and habits to improve its ability to make money from them over the course of years.

It has a lot in common with other big tech firms Google and Facebook, which are also booming. Facebook has, of course, been in the news a lot over concerns about how Russia may have gamed its platform to interfere with the 2016 election.

Not that its business has suffered. Just after it had an executive appear at a Washington hearing to face questions, it said its revenue rose 47 percent to $10.3 billion for its third quarter as earnings easily beat investor expectations.

It now has about 2 billion users, and it would be interesting to know what these people think Facebook sells to generate more than $10 billion in quarterly revenue. After all, using Facebook and Instagram apps still doesn’t seem to cost anything.

Asked if Facebook’s users really understand what business the company is in, Murphy said, “The vast majority of people don’t consider the commercial incentives that lie behind the data collection.”

Apparently what is available on Facebook is endlessly fascinating for millions if not hundreds of millions of people, but I have long since stopped using Facebook. That is because, if asked about Facebook’s business model, I would say it is obviously a commercial surveillance company.

Its core business is selling everything it can learn about its users to advertisers.

Facebook hasn’t introduced a home assistant to rival those of Google and Amazon, as it can gather a lot of data just from a user’s smartphone. And that is what makes a fear of home assistants obviously irrational, as jumping on a computer and using Google all day is not that different from speaking into a Google Home assistant.

And I simply can’t quit Google. It now provides directions to nearly anywhere we drive, lets me know when the bus is coming, gives us showtimes at the movies, lets us work with friends to divide the annual expenses for a jointly owned boat and so on.

And at work the core Google search function is so indispensable that it’s hard to remember how anyone gathered information back in 1987.

I do not want to even think about what Google has already learned about the household after years of this use.

And if Google really were smart, it would have learned enough not to pitch me a Google Home Mini or even an ecobee4 talking thermostat. 612-673-4302