Ever read Carl Sagan's great story about the "Dragon in his garage"?
You should, here it is.
www.users.qwest.net...
I will quote some of it for you.
""A fire-breathing dragon lives in my garage"
Suppose (I'm following a group therapy approach by the psychologist Richard Franklin) I seriously make such an assertion to you. Surely you'd want
to check it out, see for yourself. There have been innumerable stories of dragons over the centuries, but no real evidence. What an opportunity!
"Show me," you say. I lead you to my garage. You look inside and see a ladder, empty paint cans, an old tricycle--but no dragon.
"Where's the dragon?" you ask.
"Oh, she's right here," I reply, waving vaguely. "I neglected to mention that she's an invisible dragon."
You propose spreading flour on the floor of the garage to capture the dragon's footprints.
"Good idea," I say, "but this dragon floates in the air."
Then you'll use an infrared sensor to detect the invisible fire.
"Good idea, but the invisible fire is also heatless."
You'll spray-paint the dragon and make her visible.
"Good idea, but she's an incorporeal dragon and the paint won't stick."
And so on. I counter every physical test you propose with a special explanation of why it won't work.""
So IF the creature left 3 claw marks, it is NOT totally invisible!!!