A bubble has almost no effect on the dampening quality of the rest of the liquid, nor on the compass' precision. In fact, it gives you an advantage at holding the compass naturally horizontally (working like a bubble level).

Also, I doubt that a hiking compass must be of a top quality overall as soon as it offers good enough rigidity of the casing and the needle axis is concentric with the dial. The rest is just your skills.

By the way, if the bubble is interfering with your aesthetics sense - use a round sticker in the middle of the top glass. If you don't see the bubble you are staying calm and your compass is leveled - exactly what you need to read the compass reliably.

I've got this http://www.ebay.com/itm/New-Professional...g-/281643293201 cheap model not so long ago and love it for map working, as it is much more precise and convenient to use than, lets say, a mirrored Brunton for $50. With that construction you are looking at the dial from the side through the integrated regulated dioptric loupe, not over a confusing and too close mirror, so you see the target, the readings, and the levelness quality simultaneously in focus. No more frustration trying to see something through the narrow slit in the mirror, the lid's window of this one is fully transparent. Also it has a photo tripod mount hole in the bottom, I'm sometimes using it on my hiking stick (which has a hidden photo head), when I want to make an exceptional azimuth fix. All metal casing, even though a bit clumsy finished.