The scanners I was referring to were smaller programs put out by the manufacturers of the full programs that would simply scan files and the registry (hence scanner). They had no other capabilities other then finding and removing malware. They typically used the same definition database of the full blown programs. They were much lighter on the system, and you could run multiple of them at the same time, with the only issue really being that they would take longer to run as they were all accessing the hard drive at the same time. Most (but not all) ran from DOS prompts. Do not confuse them with the full blown programs, they were not intended for active protection.
So tell me, which one scanner will remove every threat out there. In my experience there are *NONE*. Some are better than others, but none that will detect everything on a computer. If you are earning a living removing malware from computers among other things, you want to make sure you get as much of it as possible.
The DB
Multiple scanner as in 5 antivirus scanners. You cannot do that.