It depends on the types of bugs and inconsistencies that show up in practice. If a page (or worse, the whole browser) crashes, that's a problem. If a column of

It depends on the types of bugs and inconsistencies that show up in practice. If a page (or worse, the whole browser) crashes, that's a problem. If a column of ads doesn't scale right and gets bumped down to become its own lonely row below the main content, that's kind of ugly but almost a feature.