Should Avast offer remote virus and malware scans for a fee?
There should be no conflict of interest.
Cleaning up a PC would require a few tools:
safe mode with networking
chkdsk C: /f
Msconfig
hijackthis
uninstall junk programs and toolbars
Ccleaner
malwarebytes full scan
Avast boot-time scan
sfc /scannow
defrag C:\