Having heard some of the census collectors stories on radio recently, try & be as nice & polite as possible to them when they arrive.
The basic gist was that either i) it was impossible to get answers at the door so collector had to keep returning or difficult to get past electric gates etc. ii) rude people iii) people living in fear & poor conditions. The consensus was that the collectors ended up with twice the workload they had imagined
& will never take on the job again.