Spurious keys filter Is there any possible way to filter a key space in a crypto-system to get a set of keys that decrypts out a valid text (text that is in same language or readable)?

I tried a random approach and got certain set of keys but its not that appreciative to actually required text size 

code

from Crypto.Cipher import ARC4
import base64, string, time, random
key = ''.join(random.choice(string.ascii_letters + string.digits ) for i in       range(8))
obj1 = ARC4.new(key)
obj2 = ARC4.new(key)
text = 'abcdefgh'
cipher_text = base64.b64encode(obj1.encrypt(text))

decoded_text= obj2.decrypt(base64.b64decode(cipher_text))

Dict={}
count=0
valid = set(string.ascii_letters + string.digits )
def test(s):
    return set(s).issubset(valid)

print; print 'plain text: ', text
print; print 'Actual key: ', key 
print; print 'Cipher text: ', cipher_text

timeout=time.time()+60
while time.time()&lt; timeout:
   count+=1
   key = ''.join(random.choice(string.ascii_letters + string.digits ) for i in range(8))
   obj2 = ARC4.new(key)
   decoded= obj2.decrypt(base64.b64decode(cipher_text))
   if test(decoded):
       Dict.update({'key: '+key : 'Valid Decrypted Text: '+decoded})
import pprint
print; print 'Analysis: '
pprint.pprint(Dict)
print;print 'Number of valid Decrypted Text: ', len(Dict)
print;print 'Total number of decryption performed: ', count


Output:

plain text:  abcdefgh

Actual key:  go6oMkCG

Cipher text:  JB1a3osG+es=

Analysis: 
{'key: 0UUvjzLw': 'Valid Decrypted Text: mzptBVo4',

 'key: 2beOXKN1': 'Valid Decrypted Text: Yhz3jIL8',

 'key: 3Eq7MKwu': 'Valid Decrypted Text: GA9BTdzy',

 'key: 3jUQPXs8': 'Valid Decrypted Text: 3gCa3KBG',

.

.

Number of valid Decrypted Text:  36

Total number of decryption performed:  2275140


Is there any better to sort out such keys. Such keys may be valuable to strengthen cryptography by introducing confusion
Here is the problem. For a specific ciphertext, sure you could try a bunch of keys and output the couple that result in the type of plaintext you want. But what does this really get you? For a different ciphertext, likely these same keys will not result in the same type of plaintext you desire.

Recent work on honey encryption might be what you are really looking for. It is still very new, so it should not be used in a production system without understanding all the intricacies. The authors of the paper also provide some nice theoretical foundation for the area.