People who use AMT for earning money may not necessarily be the right audience you are looking for.
Mechanical Turk seems to be filled with people itching for some community to participate in -- why not get paid for it at the same time?
Getting honest feedback probably depends very heavily on survey design, instruction sets, and, if you've been doing it for a while, reputation.
With a jobs size this small you'll get information that might be useful, but will probably be biased. I wouldn't trust it - but I would use it as a starting place.
For the incredibly low price I think it's worth it.
Do MTurkers tell the truth though? Presumably one person can run a dozen fronts so that they can answer questions that require a specific demographic. Or they masquerade as elderly females to appear more trustworthy and shame you out of objecting if they've not done the job properly or whatever.
Even in Russia it's about the average income IIRC if you assume 40-hour workweek.