Rate Vegas

We are regular visitors to L.V. about 4 times a year. Have at Sahra many times and have many points and have received comps...But recent visit last week we discovered something we do not like at all. Upon arrival we checked in and received our room key and were instructed that we could go up and put our luggage in the room even though it had not been cleaned from the just checked out visitors. We did go up and my wife saw that the bed had not been made up yet and just made mention to me that she wanted to notice when we came back if the bed linens had been changed. She noticed identifying marks on the bed spread and blanket...Well when we returned to the room she noticed neither of them had been changed. She called and asked for a supervisor to come to our room. The supervisor was there in a short time. My wife explained the circumstance and asked if this was normal, and supervisor stated that it was. My wife requested all new lines and we got them quickly...but we wonder if this goes on a lot, so we thought we would post this comment to see if anyone has had this experience or caught it. We understand that not changing them everyday while the SAME people are checked in a room. We shutter to think that we might be sleeping under linens that complete strangers from another part of the country or world might have slept under the night before we check in.