Scent-marking is a form of communication, which has territorial and personal implications. It allows cats to advertise their priority with respect to living space, objects, other cats and people. It also serves as a method of advertising the breeding status of females. Domestic cats often engage in scent-marking of one form or another and while we enjoy their bunting, other forms of marking behavior involve urine, feces, or furniture scratching. These are not as attractive to us!
When a cat defecates on its owner's bedspread or urinates on an owner's legs, this behavior should be viewed as a great compliment, signifying close attachment. However, this is often not the pet owner's interpretation.
For more information, please read Normal Behavior – Scent Marking