I guess a design could even lose a little bit of it’s magic if the grid is shown, especially for complex layouts where the grid isn’t obvious at first.

As designers, our role is to curate content for our users, to make it clear and approachable. And our best friend in presenting our content effectively is the grid, but it isn’t content itself. Showing the grid adds no value to regular user and adds an unnecessary visual element that detracts from the hierarchy of the real content.

That said, there are exceptions, namely, when the grid is actually content. One example, might be on the site of a design firm, where they’re trying to show “designedness.” In cases like that, a subtle presentation of the grid could be acceptable. But those are the vast minority of cases.

The grid won’t mean a lot to the average web surfer. They’ll just wonder why they have “squared paper” on their website. I know if I added a visible grid to one of my client’s sites I’d get an angry phone call pretty quickly.

I guess a design could even lose a little bit of it’s magic if the grid is shown, especially for complex layouts where the grid isn’t obvious at first.

Avoid them to avoid the cliche, or if a grid being displayed doesn’t match the design direction or somehow impedes the function of the site.

I think the easter egg approach as used by Analog is the nicest way. With that said, our grid at http://neutroncreations.com is on proud display in the header, but not further down where we encouraged Elliot Jay Stocks to deliberately emphasise the seemingly chaotic layout, without revealing any order behind it.