The app Face Swap Live is popular because the possibilities of successful—meaning perfectly terrifying—face swap photos are endless. This photo, from Reddit user giftigeseele, fits neatly into the category of sublimely awful face swaps. Its lines are much neater than that freaky baby/oven swap to the point that if you stare at it long enough, there appears to be little wrong with this photo.
The woman on the left looks either like she forgot to blend in her clown contouring all the way, or like restorers were able to slightly salvage the ruined Ecce Homo fresco:
The tattoo, on the other hand, appears to be an incredibly realistic tat that would induce nightmares if seen in person.