Ive seen one (cheap) 40MHz receiver which would output a valid servo pulse very occasionally when the transmitter is turned off. Since then I changed my interface code so it required four valid pulses in a row before activating.

I make my own failsafes (built into my interfaces) and would really hate to see only pre-approved types being valid, but I can see the problem. Would peer review help? Im happy to make my circuit diagrams and code available for review and to review others work.