Park in ashphalt every day at work. Last week a buddies CBR600RR sank in a bit, but not mine on the stand.
In soft sand when the side stand just goes in and can't support the bike I use the centre stand, it sinks in but the wheels end up supporting the weight and the centre stand is driven in like poles and it's stable.
Some bikes have a large arm on one leg of the centre stand, and that will tilt the bike a way off to the right, before the wheels stabalize it. I use a plastic thing I got from Haugens one summer, and I use it all the time, regardless of weather. Habits are hard to forget. Mine also has a string on it that I wrap around the bars so I won't forget to pick it up.