slope of frost free sillcock

I'm looking at a couple of frost-free sillcocks. Each one comes with a wedge-shaped half-gasket that goes between the mounting plate and the siding. The gaskets come attached to the sillcock with a rubber band. In each case, the thicker part of the gasket is at the bottom of the mounting plate. If mounted to vertical siding with the gasket in that orientation, the sillcock will slope towards the inside. If mounted on shingles or clapboards the sillcock will slope even more towards the inside of the house. This seems like the opposite of what I would want for the water to drain out when the valve is closed.
I had assumed that the gaskets were just shipped in the wrong position and should be reversed for installation, but then I looked at a similar unit installed previously by a plumber. It has no gasket, but it is clearly pitched toward the inside of the house. The geometry of the tubing is such (there is a double 90 right after the sillcock) that the angle was unconstrained by the rest of the house piping, so this was either deliberate or careless.
Am I missing something? Wouldn't it be better to pitch the sillcock towards the outside so water can drain in normal operation? I suppose pitching the sillcock (and the short piece of pipe to which it is connected) towards the inside makes it possible to drain completely from the blead port in the associated stop&waste valve, but that's the extraordinary case rather than the common day-to-day one...
                Dan Lanciani                 ddl@danlan.*com
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Instructions that came with my frost free sillcock, says install should be at a slope so unit drains when turned off. that plastic gasket is so you have a flat area to mount faucet against siding. tip sillcock downwards so it drains, otherwise you'll have trouble using it in the freezing cold

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My frost free sillcock was installed on the west side of my house facing the prevailing winds. After several years, it froze about 18 inches inside the house and split the copper. You can imagine what happened when things began to thaw out! I solved the problem by installing a shutoff five feet inside the house and leaving the sillcock open thru the winter until I needed to use it. Nothing is foolproof.

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