Another possible cause for disqualification or possible ban would be straight-line responses to a set of matrix questions.
Matrix questions is a set of questions in which all the questions/items have the same possible response (for example, Likert-style items from strongly disagree to strongly agree; SD, D, N, A, SA or variations).
It's not uncommon for respondents to give the same response for each item. Ideally, the researcher would reverse code a couple of items. With reverse coding, a consistent response would then have some mix of disagree and agree responses (see Rosenberg self-esteem scale below as an example; items with asterisk are reverse coded).
If respondents' provide straight-line responses (all "SD" or all "SA" as examples), the survey will mostly get flagged, even if no items were reverse coded.