And this is a point of some controversy. In contests that allow electronic aids (like spotting networks and skimmers), the users are generally in a separate category. In some cases you go from Single Operator to Single Operator Unlimited, in other cases: Multi-Op Single transmitter. Other contests prohibit aids of any kind, including skimmers. Most state QSO parties prohibit aids under the philosophy that while they are contests, they are for "fun" and folks shouldn't take them seriously enough to go to the effort of electronic aids.
Some of the folks that do log checking swear they can detect the use of skimmers based on the logs but decline to explain how. Being a software developer, I can imagine how it could be done. Whether it is or not, I don't know.
Needless to say there are folks that claim that all these aids ruin the tradition and spirit of contests. To others, this is just the natural evolution of technology.