I think it depends on how the question is answered. For instance, if you ask me my favorite in terms of the journal to publish my work, I can tell you that I like publishing in an education-based journal indexed in Scopus without mentioning that specific journal. I think it depends on being creative with one' s response to such question.
It depends on what data sets you reveal in the answer or are required by the question. Additionally let's assume that the person/system asking the question does not know who you are beforehand, so you have not introduced yourself nor are you logged in with your personal information. Now, with this assumption that by the point of answering the question you are indeed anonymous you can remain that way as long as you do not uncover any data-sets categorized as personal data - First name, last name, date of birth, personal e-mail address, physical address, photo, etc. As long as you stick to answering with i.e. "My favorite fruit is bananas." there is no actual way of knowing that YOU like bananas, but rather you provided data that can benefit a poll or some other statistical goal where your answer will contribute towards a higher rank of bananas. Maybe the example is not the best one but I hope it gets the message across.
Summary: You are in control of what data you give, as long as you do not indetify yourself with personal data sets, your privacy is maintained Zeyad Mohammad .
I do not think that the questions that ask about my favorite things reveal my privacy. It may be a special case and it may be compatible with some or a large number of people in RG, but this is my point of view.
First, one should never disclose one's Personally Identifiable Information (PII) for security reasons - it's a best measure to protect one from any kind of theft, fraud, cheating, ransomware, malware, spyware, etc.. PII is information allowing an individual having bad intentions to act in misrepresenting you at a financial organization, online, with any kind of businesses, government agencies, or social networks. Simply saying, keep your smart phone, documents, passwords, any kind of records, portable memories, check books, and alike in a safe place/location.
Second, various online questionaries' which are seemingly secure and do not contain PII asked question do not disclose your privacy and security only under condition that your online user account is protected from a malicious access. Since you cannot be ever secure and certain that it's not the case, it's better to refrain from participating in those questionnaires.
So called individual consumer targeting marketing tools are often used to gather information of a consumer's taste and interests in order to push to that consumer's online address personally targeted sales information.
If some one feel inappropriate to answer such questions, it is their wright. However., there are many people who feel happy and high by sharing their likes, researches, photos, opinions, experiences, expertise, addresses, workplaces CV etc..... I am also in favor of such sharing for the sake of good and benefiting others. In my opinion, this is what we feel in the progress and development of the globe. What not to be share with others may be super personal, related with family or friends in common, and they don't wish to make it public.
My personal opinion, asking about favorite, it's not an inquiry about privacy. Favorite thing commonly we share each others, like my favorite color green and game football.
Thank dr Asrar Abd-ulzahra Ali , Kamal M Alsaad , Md. Abdur Razzak Choudhury , Faraed Salman , Salah Abed Altamimy , Safaa K. Kadhem , Ali J. Abboud , Amjad Ali and Mahammad Khuddush for answering the question
They may put your privacy at risk and be invasive even if they are not linked to any Personally Identifiable Information (PII) such as name, social security number, or national identification number. In the example brought up by @Branko_Dzakula, answering "My favorite fruit is bananas", even though your response seems to be anonymous if you have not logged in, it still might be connected to other attributes and favorites of yours. Collecting information about your favorites can help advertisers to target you with more personalized ads (e.g. banana cake, dried banana, banana store!). More importantly, such a dataset might be prone to linking attacks in which someone collects information about you from various resources and by combining them, connects your answer to your identity. For instance, if besides banana, you like skydiving too, your set of favorites will become uniquely identifiable and connected to you if your friends know (let us say from your social media profile) that you are the only person between respondents who likes skydiving.