How many of these bad installs are there? How many don't get reported on the the board? With millions of users I think it would be quite high.
What you see on the board [forum] are the problems. Users who don't have problems do not report a problem and few come here to give a compliment although we do get them from time to time. So given the millions of users of Avast, there is a low percentage of people with "bad installs."
Many times, these "bad installs" can be contributed to conflicting security software that the user has on their system, remnants of previous security software that they [the user] are responsible for removing (not the company who they are going to install new software), existing malware preventing an AV from being installed, hardware problems, and firewall issues (connectivity for updates).
The user is ultimately responsible for their machine, including reading and understanding the EULA of all software. Do you read all your software EULA's? Most people do not. Most people when installing software do not read what they are clicking and just click "next" or "OK" without reading. Can you list how many AV's, FW, and other security software you had on your machine since you have owned it? You should as a responsible owner of that machine since you also should have uninstalled it by the vendor's uninstaller tool and not some other way which may cause problems down the road with another security software. Do not blame Avast for a "beta program," which it is not...the problem is that people need to be responsible for their machines. We are here to help them when they need assistance because we know that not everyone does what I have outlined above.