The rubber maid hides don't HAVE to look tacky with a little bit of effort, and in the long run it's cheaper for you to usually make your own as I've seen large decorative hides run upwards of 20$ each.

Depending on how crafty you are, you can make them very decorative, and still get teh functionality.
Go out and buy some cheap non-toxic craft paint in a couple shades of grey or tan, and a bottle of clear waterproofing sealant, and some decorative leaves (and a hot melt glue gun with some sticks).

If you are crafty, buy some sand paper and paper mache supplies as well, sand the rubbermaid a bit to make it rough so that the paper mache will stick better, and then use it with some newspaper strips to add some texture to the rubbermaid (just the visible outsides). Let it dry completely for about 24-48 hours depending on how much you gooped on.

Then paint the rubbermaid with whatever you choose as your base colour (usually the lightest). Let it dry, and then get some of the darker colours - mix them with a bit of the waterproofing to make them a bit opaque and add some shading - if you used the paper mache this looks best when it's put in any grooves or lower areas. Let that dry, and then completely cover it with the waterproofing sealant. Once that has dried, hot melt glue some of the decorative fabric plants to it as well, and you've got yourself a hide that is both functional, and looks like a vegetation covered rock.

If you don't like the natural look, you can pretty much do anything with a bit of imagination and the right supplies.