I use AVG anti-virus/spyware software regularly and it detects things from time to time; I also use Windows Defender and malicious software removal tool occasionally but they never seem to detect anything. Finally, I use Advanced Windows Care 2 personal periodically and this detects loads of issues. Why the discrepancy?
Easy.
AVG is anti-spyware and anti-virus, but not a very good one.
Defender is anti-spyware only.
Windows Care 2 is anti-virus.
Different protections for different types of malware.