I came across this 6-minute video on how to identify and avoid greenwashing when buying cleaning products or hiring someone to clean your home. The carpet cleaning blog where I found it seems, uh, rather informally managed, but the info appears generally reliable.
It's really a Maid Brigade commercial embedded in the video, but the advice is sound, and if you skip the last 45 seconds, you miss most of the commercial. I like the five questions (opens PDF) to ask when hiring a cleaning services - although #5 is for those seeking perfection.
Personally, I prefer to hire locally, to keep the money in my local economy, to ensure whoever cleans my home has reasonable control over his/her hours and working conditions. Plus, I'm happy to help share green cleaning along the way - expanding the number of green cleaning services available in my community.