Why should I use a professional carpet cleaner over a DIY machine I can hire from the store?
DIY machines are cheap, no doubt about it, and they do remove some soil. However, they do leave residues from the cleaning products they used, and they do take a long time for carpets to dry when using those machines.
Another issue that you get they do let carpets resoil quickly.
Professional cleaning, no doubt about it, it costs a lot more. But it will remove a lot more soiling from the carpets. Using the correct solutions and more powerful equipment, they also leave the carpet a lot dryer quicker.