The answer;
How good are your legs
If they are good enough you can ride with the most hateful of spurs and never touch your horse
or
You can ride with the nicest of spurs and leave spur marks.

When you are good enough you can add artificial equipment, you should be able to "just" touch your horses side for .5 seconds and leave it alone.

If you have a dead sided horse, maybe he's just been trained to ignore the leg, since it is always flopping around, banging, squezzing,hitting,gripping.
He's just doing what it's been taught.

Want to know if you legs good enough, look @ your saddle and your boots/chaps, there shoudn't be rub marks from your leathers.