I think the main problem would be that potential thieves would be sizing up the place. However, to take the question further than Open Farming and into the field of Open Politics, I think a better idea would be to institute a system whereby Inspectors appointed by the NFU would visit the homes of politicians and inspect them to ensure that all the regulations they impose on us have been adhered to.
I can think of the checks required on electrical equipment, safe storage of chemicals, disposal of rubbish, burning of brash, burying of deadstock in the garden, employment of au pairs, sites visited on-line etc.
What else do readers think our representatives should inspect during their surveillance visits to the homes of our MPs?