Recently I saw a thread about avast's data collection or some sort, and I can't find it anymore. So my question is: does avast collect any kind of user data? And if so, what is collected?
The EULAs my help. https://www.avast.com/eula In short, yes avast does collect information, much like many other AVs these days.
You have to collect data if you want to make good use of cloud systems. If you don't, you may just as well not have them...
This is report made in 2014 regarding the data transmission in well-known security software. Avast is in there http://www.av-comparatives.org/wp-content/uploads/2014/04/avc_datasending_2014_en.pdf
I suppose the amount of data gathering depends on the services opted to use during installation. Toolbars collect data and URL filters would most probably as well. As has been stated earlier, for a cloud service to have any real efficacy it would need to collect some data. I think it is to be expected. Whether Avast! or any other particular company uses that aggregate information for nefarious purposes is debatable. I see it as an acceptable trade off, I get a good customisable and effective product for free and they may benefit from data mining me.