Ha.  I was same way.  I clicked the "X" in the upper right and instead of closing the ad it took me Brighthouse website....   I thought the ad was a joke when I saw it and it ballooned to take up the full screen.  Maybe I'll get into winery and vineyards.  But I am the product.  I do appreciate company news on SA, but that's pretty rough.

I think the way mute works is that everyone else in the world can still see the comment. Mute only removes comment for the particular user that implements that mute.  Everyone else can see the comment.  It only works for personal curation of your feed.  Doesn't impact what others see.

I think if you click the mute option it toggles mute.

Since the discussion above, SA added a "Mute" feature.  Out to the right of a comment there's a dropdown arrow that gives the "mute" option.  Unless you're a paying member you only get 3 mutes, but that might help.  

Just to followup.  I hadn't read many SA articles in a while - I mainly read the conference calls - but investing boards I've been a part of have a strong tendency to fill with sniping political content unrelated to company performance and that tends to run off users interested in investing.  I'm concerned that is happening at SA, and it is causing me to read comments less and unfollow threads in which I have interest.  The thing is - there are some really smart and insightful comments - but I ask SA to let me turn off the unhelpful commenters.  

I've supported a feature like this in the past and want to express support again.  I don't understand SA's reluctance to not enable us to better self-curate the commenters we see.