Trust In Politicians.

A recent poll showed that people, by and large, have precious little trust in our politicians BUT they do tend to trust their own constituency MP.
So how is this anomaly possible?
Here are my suggestions:
1) The MPs tend to work well in the constituency itself as do so many councillors of any persuasion.
2) The MPs cast off constituency shackles as soon as they get to The Palace Of Westminster and their true, anti-democratic face is revealed.
3) Some voters are extremely naive.