There are many ways to lose height and speed, but to lose them at a high rate is generally inefficient. Flying dirty and/or at speeds that differ from your scheduled economy speed is a waste of money. It also gives a pointlessly uncomfortable ride and makes you work a little harder. It's also something that can normally be prevented, if only a bit of thought had been invested by the relevant parties beforehand. At busy airports, ATC generally has a grip on the process but at secondary and tertiary airports too many controllers want to play controller with you. Many also have pathetic "noise" and pointless local procedures. Procedures that require you to fly seven mile finals, rules that prohibit visual approaches, statements of intent regarding CDAs, yet controllers who won't give you a descent.
General numbers: 10 knots per mile and 3 to 4 miles per thousand feet.
But if you are the enemy, how about just letting us get on with it and only interfere if it looks like we are going to bump into something? Or is that a little too controversial?