To start with, who was conducting the interviews and in what language? Were there interpreters and who were they? If no interpreters then they must have interviewed people who could speak English well enough. What percentage of the population is that?

TFT study PDF link:

Methodology:
This survey was conducted by Terror Free Tomorrow: The Center for Public
Opinion (“TFT”) and the New America Foundation, with fieldwork by KA Europe
SPRL. Interviews were conducted by phone from a CATI facility in the region but
outside Iran, in Farsi. They were conducted among a random national sample of
1,001 Iranians aged 18 and older from May 11th to 20th, 2009. The exact location
of the CATI facility is not identified in order to maintain confidentiality for the
interviewing team. The questionnaire consisted of 31 substantive questions, 17
demographic questions, and 24 quality control questions.
During the course of fieldwork, there were 2,364 contact attempts made. Of
these, 625 resulted in non-contacts, yielding a non-contact rate of 26.4%.
Another 39 contact attempts resulted in non-eligible respondents because they
were not Iranian nationals, and 8 respondents were never available for scheduled
call-backs. Of the 1,731 successful contacts, there were 730 refusals giving the
study a 57.8% response rate. The last poll conducted by KA/TFT had 54.5%
response rate. This poll has a +/- 3.1% margin of error at the 95% confidence
interval.
TFT and KA use telephone interviewing instead of face-to-face research in Iran
because of the political and social constraints inside Iran. Face-to-face
interviewing in Iran can be difficult for interviewers who risk possible
prosecution and imprisonment. Face-to-face interviewing also poses issues
related to access to households and respondents due to social considerations.
Access to female respondents across the Middle East can be challenging.
These problems can be overcome through the use of CATI research in Iran. Iran
has an estimated national land-line telephone penetration rate of over 90%,
which gives it a higher telephone penetration rate than most other countries. The
high percentage of landline households also reduces potential bias from cell
phone-only households.
Interviews were conducted by 21 trained interviewers who are native Farsi
speakers, and have worked on numerous other surveys into Iran. Interviewers
were briefed on a number of items including, but not limited to, the objective of
the program and survey details, selection of respondents, the questionnaire (both
asking of questions and recording of responses), timing and control issues, and
usage of the CATI system. Interviews were subjected to numerous quality control
procedures, including direct supervision of all interviews by a supervisor
experienced in Iranian surveys.

See more on pages 25 & 26. Sorry for the rough formatting. I copied straight from the PDF.

Going on, how much did these researchers know about the country and different sections of it? How much did they know about what is and what is not allowed? For example, it sounds to me quite credible that people would not worry about making some general comment about electing the chief mullah, knowing that it is not the issue but will probably balk at saying the truth about who they are going to vote for. But then I recall being told with a straight face that the Soviet Union was a pluralist society. A different kind of pluralism, of course, but a pluralism nevertheless.

And BidEdsBlog is correct in his assessment of who runs the elections start-to-finish. Only the Supreme Leader has that power (kinda what His Hollowness is reaching for, without the obvious armed militant backing).

Years ago I traveled the world on humanitarian trips helping children (Uganda, Ecuador, Brazil, Bosnia) and I often said that some day, because of the crooks in Washington and so many ignorant Americans, America would become a third-world country. Maybe my prediction will come true. Hopefully it won’t be in my lifetime. We reap what we sow.