I recently bought a new bedding set including an expensive dark grey M&S Egyptian cotton bed sheet. The washing instructions say 40 degree gentle wash. We’ve had them on our bed for a week (first time using them) and I washed them today, tumble dried them and put them back on the bed. Where me and DH lie (shoulder height, just below pillows) are a small circular grease mark on my side and huge grease mark on DH’s side. It looks like two damp patches. This often happens with DH’s pillows which gradually turn brown/yellow over time but I can’t believe that after a week of use the expensive sheets look so awful with big grease patches. Please can anyone advise what on earth causes this and if there’s any way I can rescue my sheets 