If someone requests a particular free A/V, that is exactly what they get. If they don't, they get MSSE.
I default to it for a number of reasons. Mostly it's a tiny download, a fast install, it's very light on system resources and runs on older system pretty well, it detects well enough, it negates Windows Defender in Vista which would otherwise want to run and consume more resources with a 3rd Party A/V installed, and also it's Microsoft so people actually have brand recognition with it vs. the likes of Avira/Avast/whatever else others use.
But they always get the conversation from me, rather disclaimer, that I don't *recommend* MSSE, or any A/V for that matter paid or not, over another - and I usually do a pretty good job explaining why I won't stake my rep on something as variable as a particular A/V's reliability, especially when new malware is introduced. When they understand this, it's a lot easier to deal with them should they get an infection in the future while running that A/V I put on their system...
It does. Fake A/V in the shop a few weeks ago had the big K on it. It wasn't functioning properly as I recall and needed a reinstall - unsure if that was the malware or just a malfunction...
But personally this is a very rare event for me to see. Not sure if it's because Kaspersky is so rarely used among my customer base or if it's just that good against all the fake A/V floating around out there these days. *shrug*