As a serious coffee drinker, I'll chime in on those types of stains.
If those are coffee stains, they CAN come out. Personally, I use Tuff Stuff (available at WalMArt, Auto Zone, etc...). I have also used Hot Shot and a few others with success. The Tuff Stuff seems to work the best for me without leaving a horrendous smell (Hot Shot smells like solvents), but Tuff Stuff does not have a really pleasing aroma itself. I vacuum up loose dirt, spray Tuff Stuff on the stain, and scrub with a fingernail brush lightly. The scrubbing is more for working the foam into the carpet instead of working the stain out. Let set for a minute (but don't let it dry), then blot and rub the stain out with a white towel. It may need repeated. I then follow up with steam cleaning the whole area (using either my Thermax or hoover Steam Vac with hot water). This is necessary to blend in the clean spot.
Another option that I use on really nasty mats is to vacuum, spray with an APC (I use Orange Blast 4:1 like you did), scrub, and then pressure wash with my 1300 psi pressure washer. I use a broad fan setting so as not to damage the fibers, and it really gets things out that you never knew were there. Coffee stains come out easily this way, too. Using this method will amaze you as to what your vacuum (in my case a Rigid 5 HP or my Thermax) leaves behind. Even pressure washing after steam cleaning gets an amazing amount of crud out. After pressure washing, use a shop vac or steam cleaner to suck the majority of the water out (and remaining crud). Then lay them in the sun for an hour.
Problem a lot of people run in to with removing most stains is using the wrong cleaner. I read on a site that stains are put in to 3 categories: organic (carbon based like blood, grass), inorganic (non-carbon based like dirt) and petroleum (oil and greases). Generally, most APC's are good at removing petroleum stains, laundry detergent is good for inorganic stains, and Oxi Clean types are good at organic stains. They just aren't as good getting out stains they aren't specialized for, although they may still work. Matching the cleaner to the stain makes life so much easier.
there are many sites with "tricks" to cleaning different stains. Check out
http://www.tide.com/staindetective/selectStain.jhtml ,
and a quick search revealed
http://search.netscape.com/ns/boomf....com/Top/Home/Homemaking/Cleaning_and_Stains/
It is a good list of sites on how to clean A LOT. Good info from the sites listed. Mods, this may be good for a sticky.
Sorry for the length, but hope this helps (I hate interior stains, which may explain my lengthy reply).
Dave