Even if your cell phone is devoid of spyware, your phone can still betray your cheating ways. Like the browser history, most mobile phones keep a history of recent calls. If your spouse knows your password, or if you don't have the password protected, it only takes a moment to check the device for dialed numbers, and possibly names if you have your paramour's contact information stored. The same goes for text messages, which can be even more incriminating than a frequently called number, especially if you've engaged in sexting.
There is a Call and Text Eraser app (Cate) for Android that was designed for texting on the sly. It hides the app when you shake the phone, doesn't put an icon on the home screen, lets you hide numbers from your contact list and creates hidden call and text logs. But no app is foolproof. If someone else installed it on your phone, it could be used as a spying app to hide secret call logs on your phone.
There is even a cloud service called Uppidy that allows users to save their texts to the cloud, which, if you, your partner or, say, a company providing you with a phone, sign up for it or a similar service, could create even more chances for unintentional self-incrimination via a digital trail.
And even those who are crafty enough to password protect, delete history and use privacy apps can still be betrayed by the phone bill itself, which usually lists the phone number, date, time and duration of every call you've made each month, and may contain similar information about texts.
Your phone company may even keep copies of texts you've sent, at least for a little while. They could be kept for hours, days or months, depending upon the situation. Most companies are deleting them faster and faster as their server space fills up. And getting copies, even of your own texts, currently requires a court order. But this is another indicator that anything you send may not be as temporary as you think.