sentences:  Although the surface of a mattress can be cleaned with a vacuum cleaner, it is very difficult to completely remove stains from most standard mattresses.An unprotected mattress can become marked or stained quite quickly as natural perspiration produced throughout the night passes through a standard cloth sheet and creates a characteristic yellowish-brown tidemark where it has been absorbed into the upper surface of the mattress.Mattresses are also susceptible to many other contaminants.