Don’t Use The Placeholder Attribute — Smashing Magazine
A lot of the issues here are with abuses of the placeholder attribute—using it as a label, using it for additional information, etc.—whereas using it quite literally as a placeholder can be thought of as an enhancement (I almost always preface mine with “e.g.”).
Still, there’s no getting around that terrible colour contrast issue: if the contrast were greater, it would look too much like an actual pre-filled value, and that’s potentially worse.
