For the past few weeks, almost every time I link directly from Google into a question I see the "Welcome back! If you found this question useful, don't forget to vote both the question and the answers up." banner. I've clicked the "hide" link at the bottom of that banner. It will seem to keep it hidden for a little while (in other words, for the next few questions I click into), but then it will show up again a day or two later. This seems like a bug...
This isn't a bug, this is by design:
only appears if
If you are a very infrequent visitor, yet tend to hit a lot of web search results... you might want to log out. But you really should be voting up all those search results if you found them, and they are helping you!
The current criteria for choosing when to show the banner are IMHO overly aggressive and will only get worse as Stack Exchange grows. I frequent two or three Stack Exchange sites, but I visit many of the others infrequently. I prefer them to other Q&A sites, because I know they work. But every time I go to a specific Stack Exchange site that I haven't been to recently enough for the current criteria, I get this message.
The message detracts from my experience because:
Suggested improvement: I suggest the current criteria be expanded to include a condition that checks your frequency of activity across all Stack Exchange sites. "Activity" can include voting not just visiting, and then the message will get to the right people. Clearly targeting this message at people who already vote frequently is unnecessary.
Those of us who are frequent users of the system-at-large, but not that specific site, shouldn't have to put up with this. To be clear, this is making Stack Exchange worse for me, and the impact is increasing as the number of Stack Exchange sites increases.