We rent them from time to time. They work ok. You have to scrub beforehand to get the spots really clean, then sometimes another scrubbing afterwards.

Never done professional, so I don't know if they do it better

I have always rented the carpet cleaners from Safeway, not sure if it's rug doctor or not, but they work well and are cheaper then calling in the professionals.

We have also rented the Safeway machines and had good luck.

In between machine rentals I've used Woolite carpet cleaner to get stain spots. I've had decent results, not perfect, but good.

Invest in a Hoover steam vac -- about $180. While not as powerful as the ones you rent, you can use it more often - for better over-all effect. I have a cream-colored area rug in the living room, and with the Hoover kept it reasonably clean for over 5 years now -- and I have two kids!

Recently, a friend of mine spilled a glass of red wine on my off white sofa. I was so sure it was going to require a pro cleaning job that I didn't even want to run to the grocery store to get some cleaner. He insisted and we ended up with something called Woolite Oxy Deep. It actually completely removed the wine stain. I have since used it on my wool rug in the living room to remove some minor dirt and staining and it works beautifully. The only problem is the area where the spots were are so much cleaner than the rest of the rug. I would suggest using something like the Oxy Deep on the spots and stains first before doing the general steam cleaning. And make sure you have a waterproof barrier between your rug and the hardwood floors when you steam clean.