Question wording makes answers unreliable because words often have different meanings for questioners and answerers. Moreover, in Maggie Nelson’s words, there’s “no cure” to this problem. Here’s Nelson writing about sex/gender/transgender/gay/lesbian/straight matters and the meaning of pronouns:
“When making your [Maggie’s lover] butch-buddy film, . . . you and your co-writer, Silas Howard, decided that the butch characters would call each other `he’ and `him,’ but in the outer world of grocery stores and authority figures, people would call them `she’ and `her.’. The point wasn’t that if the outer world were schooled appropriately re: the characters preferred pronouns, everything would be right as rain. Because if the outsiders call the characters `he,’ it would be a different kind of he. Words change depending on who speaks them; there is no cure.”
For more information about how question wording skews answers, see The Problem with Survey Research, esp. Part Two and Part Three.