It depends on the artist for me.
When I first follow someone I give them the benefit of a doubt and will go, after a while if it's all just constant messages of what feels like spam (it's a feed related to your comic. Not a twitter wall) then I will skip them over depending on the artist.
But most of the time I don't mind checking them out. I like a side drawing (related to their comics) here and there, I like seeing a creator get excited about subscribers, I also like when authors put an effort to communicate with their fans (it's even something that is encouraged when you are making a web comic) but ONLY if it's on topic so to speak, as in, I don't appreciate the "WHO SAW THE NEW AVENGERS MOVIE?????" quote unquote 'announcement ' or a "I drew a fanart look." or "I felt like drawing random guys making out look" as even though still art from the artist, these are kinds of pictures I kinda see as spam, because they have nothing to do with any of the comic series that I am watching them for, and if I see an announcement I want to be something related to the comic I am reading at least.
The issue with the wall system is that is is extremely poor when it comes to management and what you can do on it. So literally everything gets melded together and pushed down by other things because there is absolutely no way to organize or prioritize posts other then the 'notify subscribers' button. It's why I don't like the 'Thank you for Subscribing' wall posts, because I seem to get the majority of them after I do an announcement post like "I'll be on hiatus for a bit because I'm in the hospital" or "Thank you for helping me read ____ number of subscribers here is a gift illustration to celebrate" and then people miss it because it will so quickly be pushed down by 'thank you' posts and depending on your update schedule, your own updates. The best option is 'notify subscribers'. You can't even pick which fans you send it to if you work on multiple comics, because sometimes your announcement (extra drawing especially) does not relate to ALL your series.
It's not a good system. At all.