There are several ways to see someone is offline or just set it to the status YM invisible.
1. Checked by using sites that provide such services.
The following list of sites that provide such services:
www.vizgin.com
www.invisible-scanner.com
www.ydetector.com
www.4invisible.com
www.invisible.ir
www.detectinvisible.com
www.statusdetect.com
www.invisibleyahoo.com
www.yahoo-status.com
www.2oost.com
www.buzzu.info
www.vizgin.com
www.yahootracer.com
www.yahoo-on.net/
2. Using IMVironments facility.
- Login first with the IM you.
- Click 2 times your friend ID which will be seen
- Click IMVironments -> Yahoo Tools -> Doodle ..
- Having appeared "Waiting For Your Buddy to load Doodle", wait a few seconds.
- If it changes Doodle "Blank", meaning he Invisible.
- If the situation remains the same Doodle means he Offline.
3. Using Buddy Spy software.
You can download it at www.buddy-spy.com.
After the software is installed you can click on "Scan Options" and enter the ID that we pengen detection.