Is being able to see your veins through your skin considered unhealthy?

Not necessarily. Some people with fair complexion, or lean and or muscular build will be able to see veins through the skin. This is normal. If you have symptoms in your legs of heaviness, aching, cramping, restless legs, or ankle veins with pigmentation or other skin changes... Then this would tell you to see a vein specialist called a phlebologist. to find one in your area.