My DH's family owned a carpet, flooring, upholstery, fabric and drapery store. He has installed carpet as a business but does not have this business now. We have always used the hot water extraction ( steam) for cleaning carpets. Usually once per year. I have never noticed any ruination of carpet. Ever. Many different carpets. All types. We have had companies do it for us (meh) and I have rented the rug dr from the grocery store and that is actually what I prefer to do.

I have white carpet in my BR and when I rent I use pre-spray, then about half the recommended cleaner and I go over and over it with hot water until water is clear. Takes awhile. Lots longer than the once and done with the hired guys.

We had a rental once with especially filthy carpet that was good quality, I did as above then my DH re-stretched and it was like new.

You will be amazed at the dirt or maybe I am just a slob but I would go for it.

We just put new "silk" carpet that's part of the brand/ style name in our new BR. We are a bit leary of the backing on this new type of carpet as to how well it will hold up. Seems cheap but the carpet was not, so we will see.

I have always 'steamed' our carpeting and frankly rip it out because I am read to redecorate before the carpet wears out. Usually 8-10 years max.

Last week I took scubbing bubbles, a garden hose, and and a push broom to two vintage wool rugs. Dried in the sun. They are fine.

We once hired a service to do our wall to wall carpets. Before and ever since, we have rented a machine from the supermarket. It does a great job, it's much less expensive, and you can go over it again and again until all the dirt is gone. Exactly what missymoo said in her second paragraph.

Carpet manufacturers recommend hot water extraction (steam) cleaning as the most appropriate and effective method of removing stains and dirt while protecting the carpet fibers. I've always steam cleaned and our carpet (a 6 fiber nylon) is still is excellent shape going on 15 years. I sort of wish it didn't look so good as that would make it easier to decide to replace it.

While others have been satisfied with renting a machine, keep in mind that the suction power isn't as great as with a professional truck-mounted machine. And, using soap without enough suction and power is a good way to leave residue which attracts more dirt to your carpet.

I have had mine professionally cleaned (not impressed), rented the Rug Dr (heavy & lots of work) and finally bought a Bissell to deep clean. I am sure it does not clean as well as the Rug Dr but I am amazed at all the dirt that comes up.

Also with pets and children it is good to have on hand. Some of my carpets/rugs can get by with a once a year cleaning but others need it more often if just in select areas. Having my own allows me to clean as needed.

I rent the machines 2-3x per year and do it myself. You need to find a clean and working rental unit. Hard work, but usually no problem, with the exception of trying to hold up my king sized bed; for that I need to get a helper.

Funny you should ask. I spent the last 2 days on a deep cleaning binge.

There is a GW thread regarding cleaning silhouette window blinds and I
just purchased a lift-off carpet cleaner to do that, with great results. Then I
got carried away and cleaned just about everything in the house. I would never hire professional carpet cleaners again. I
have used both ChemDry and professional steam cleaners, but I think this
did a better job because as Missymoo said, you can keep at it until it's clean. This has a tool to get close to the baseboards. No
professional carpet cleaner has ever gotten the edges as clean as I did. I
also added a little oxy to the cleaning detergent, but my carpets are pretty light.

In my experience scotch-guard is removed during the cleaning process and carpets
get dirty faster. Maybe that's what your DH means when he says cleaning ruins them. I usually spot clean new carpets for as long as possible for that reason.

I purchased mine at BJs. It is similar to the one linked below. There is a special tool that captures pet messes in a small container which is a nice option.
Lift Off carpet cleaner

Stanley Steemer and Chem Dry are a real waste of money. They do not extract the dirty water.

Rug Doctor rental is not bad. Very heavy though and if used as often as I need it with my old dog it gets pretty expensive.

Best cleaning ever was a small private (not franchise) company. Amazing results. If I could get by with one deep cleaning a year that's what I would do, but I need 3-4 times a week.

I tried several home machines. Only the original big Green Machine about 15 years ago did a fine job of extracting. Extraction is the key. If you can't get that filthy water back out of the carpet almost completely, then it's just eventually a worse mess (not to mention what it does to your subfloor).

What I found by inquiring on here is this

Hoover SteamVac Carpet Cleaner with Clean Surge, F5914900

The price varies a lot, so follow it. I got mine in June from Amazon for $101.00. It was $120 at several other places online and on-ground.

I have now used this machine between 1 and 5 times a week since I got it in June. (That's the price of ancient dogs.) I am amazed. It is lightweight and maneuverable. It holds a 1/2 gal of water/cleaner. That "small" amount is a bonus because it is much easier to carry the dirty water container. It is very easy to keep really clean. No trapped dirt areas, brush rollers come out easily. (I always wondered what bad stuff remained in a Rug Doctor from previous users. I did my best to return it clean, as I think many would do, but there was always filth remaining in the brushes and dirty water tank.)

The very best part - this thing really cleans and really, really does a good job of extraction. I can go over and over and lay down quite a bit of solution because the extraction is so good. There is only slight residual moisture remaining which dries completely within a few hours. Bonus - watching the extracted water getting more and more clear. Very satisfying.

If you have a lot of super energy and a very small budget then do it. I did it once in my younger years and now would not think of doing it. I usually alternate between calling Chem dry and a steam cleaning service. I don't think it ruins your carpeting at all especially if it was quality stuff.

I have always used Stanley Steemer. When they leave, the rugs are nearly dry. Just don't get them cleaned on super cold days in winter, and they'll dry quickly. They also do our tile and grout in the kitchen and bathrooms.

I think Stanley Steemer and ChemDry are franchises, so the work quality may differ by their assigned geographic areas. I wasn't lucky to have high quality.