have you any way to test that any browser extension or phone apps are well installed ?
for example, a permanent page on http://adblockplus.org (http://adblockplus.org/verify-installation ?), displaying the result ?
it could be easy to implement :
<img src="http://adblockplus.org/verify-installation/result.png" alt="If you see this, ABP is well installed" />
if the result.png is blocked, the alternative text is shown and the user knows all goes well.
if the result.png is shown, it displays a bad news

this might require a permanent page and a hardcoded rule to be sure, but it could also help better diagnostic on forum.
What do you think about that ?
thomas