I think that it is worth adding for solcroft's information that the avast scanner provided for a "quickscan" in the context menu for a device/folder/file is in fact a thorough scan as defined by Vlk.
In the case, for example, of a USB device added to the system and thus scanned it would detect a malware signature in a file named 1.ini (agreed it would be bypassed as noted in the autorun case).
This is also the scanner recommended to avast users for scanning all downloads.
