It appears that imgoat only scrubs the metadata for files uploaded with file extension in lowercase. So any image with uppercase file extension or without file extension remains untouched. For example, if "mypicture.JPG" or "mypicture" image contains metadata about the device and gps coordinate, that information remains intact after uploading. The altitude coordinate, if available from smartphone/tablet devices, can also be exposed. In the worst case scenario, someone could figure out a person's latitude, longitude, and altitude, along with other metadata.
Examples of images containing metadata: