Mac's don't need defragging as OS X automatically writes 2Gb or below sized files to one contiguous space on the drive. There are certain cases where's it's needed to free up a large spaces on the drive, but not something everyone has to do.

The best app to clean mac is a self-regulating software that won’t need your human intervention and will do all the tough job for you. However, you can easily switch to the manual settings and adjust everything to your needs and preferences. But the reason it’s the best app to clean up mac is just that the background option is so much. In addition to its Android and iOS apps, there is a web version of Clean Email that works in all major web browsers. As such it doesn’t really matter which operating system you use because Clean Email is the best email app for Mac, Windows, Android, and iOS users alike. CCleaner for Mac! Clean up your Mac and keep your browsing behaviour private with CCleaner, the world's favourite computer cleaning tool. Smart Mac Care is considered one of the best cleaning apps for Mac. It comes with advanced features and a lot of abilities that make your device work much better. This app keeps your Mac safe from malware, trojans, adware and it detects and removes all the unwanted junk files from you device. You can get this app for $59.99.

Macbook Cleaning App

Being an Apple products aficionado, and to keep them in good condition, I’ve been using many cleaning apps for my iPhone and MacBook. I’m listing some of the free Mac Cleaning Softwares and applications for you guys out there who have clogged up PCs and need some memory. #1: AppCleaner One of the easiest to use Cleaner of all is AppCleaner.

Far as other Mac maintainence, there really isn't any except to backup one's files regularly. Keeping Software Updated and run a web browser check to make sure the plug-ins are current.

For Safari and Flash, this check is more accurate

Most of those cleaning programs are junk, especially MacKeeper.

If your friend got onto your computer and visited a bunch of adult sites, then I would recommend something like OnyX, doing ALL the cleaning and maintenance aspects and rebooting, perhaps followed by a Disk Utility Erase free space.

CCleaner beta is out for OS X, used on PC's and combines cleaning and scrubbing of the drive if setup correctly.

Best Free Apps For Macbook

If your interested in performance, read my post here

Best Cleaner For Macbook Pro