People who do surveys have such a touching faith that people answer truthfully and no awareness that a silly question gets a silly answer. Quite sweet really, but a waste of money.
Personally I love people being sarcastic when they are annoyed because I take them at face value and then they are stuck, do they:
1. Let you go thinking you think they really mean it.
2. Sound silly by having to explain that they didn't really mean it.
I am quite good at it so I expect a researcher might conclude that I didn't understand it! 
The last time was at a supermarket checkout where I just politely asked someone to let me get past. She seemed to take great exception to this, got right in my face and said that she was 'most terribly, terribly , terribly sorry that she had inconvenienced me'. I just gave her a nice smile and said it was perfectly OK and not to worry about it. After she had moved off the checkout woman said 'I think she was being sarcastic'- to which I replied 'I know she was!'
I have done it online too and it works a treat! I was having a great argument with someone who made it perfectly clear that she couldn't stand me or my ideas. When she got really annoyed with me she wrote a really sarcastic post, meaning the exact opposite of what she wrote. I chose to take it at face value and thanked her- she couldn't resist and had to explain- sounding a real prat!
You should try it, if you don't already, it is great fun.
I go by 'sarcasm is the lowest form of wit' and get my own back.
If researchers take this to mean that I don't understand it then I'm not bothered!