Is it possible to unpad a file that is not padded I used "AES/CBC/PKCS5Padding" to encrypt some files. But I did not provide any identifier to detect if the file is encrypted or not. Now one way to detect if a file is encrypted or not, that I can think of, is to try to decrypt it and see if there is a padding miss match. 

Now my question is, 
Is it possible for some random file to match the padding scheme?
Yes, it is quite possible that after decryption, a file that was not encrypted falsely appears to be encrypted with correct padding.

For a file of random byte length, there is probability 1/16 (6.25%) that its length is that of a valid encrypted file, and then there is probability just below 1/255 (≈0.392%) that after decryption, the last block ends with 01, or 0202, or 030303, or 04040404...

All in all, nearly one random file (of both random length and content) out of 4080 would wrongly pass the test.