Someone has asked in another thread "how do you do a reverse image search"
So you are looking at a profile and the pic's look a bit dodgey.
Place the cursor on the image.
Click and hold down the mousekey.
Drag the cursor up to the address bar.
The cursor will change to an Arrow with a + underneath it.
Release the mousekey, the url in the address bar will change.
You now have the link or address for the image.
Right click on the address and select copy
Go to google images.
in the search box you will see a camera (right hand side).
Click on the camera and paste the address into the search box.
If you get any results, open them in a new tab.
compare the results to the profile photo's.
If the images match submit a fake photo report.
If you dont get any hit's with google you can search using tineye