There are a lot of users of random MAC addresses, so although they may stand out, they would stand out in a pretty big forest. Standard practice is to set the "locally assigned" bit; the bit pattern of the last octet is xxxxxx10 (not xxxxxx01 as was incorrectly stated earlier in this thread.) This gives 46 bits of entropy, and cannot by design collide with assigned values.
If you care about stealth you probably need to reassign the MAC with some regularity.