I am a member of Apt Assn and do credit checks on prospective tenants. I have done one on my own credit as well. I think there is little damage done getting the cards for miles and dumping them. We get them a lot and there is no indication of a problem. The real damage is when you do not pay on time. Consistently. Or have too many cards at once indicating that you have access to too much credit. Other obvious stuff. There are small dings if you apply to more than one lender while shopping for car or home loans. Small stuff compared to the hit if you are a deadbeat.