"... but the very length and complexity of the survey..."

Wot?

Maybe for non-English speakers, I'll cut people some slack when they have to put in extra effort to understanding the questions. But for everyone else, that survey was quite easy to understand, and it only took me 15 minutes or so to complete it (and I carefully pondered each question and added comments when prompted to).

Maybe people aren't used to doing surveys at all?

Your games counter isn't zero. Was that all DLC and gift codes? Or are you saying you've spent more than that in the time you've had your account? (I Definitely haven't spent nearly that much recently and still got the survey this time BTW.)

I think GOG likes and wants getting skewed samples.

Months ago I made a post in GOG's "Sticky" thread, which I only saw in the first place by sheer, miraculous blind luck, even though I literally never see any of the content in 99.9%+ of all GOG Sticky threads.

They were asking if GOG should make Delisting Announcements into Sticky threads, and they were asking the question in a very biased & loaded way, by putting it within its own Sticky thread.

Thus, GOG was skewing the answers they received to be biased answers from a sample of almost-exclusively pro-Sticky advocates, whilst GOG was simultaneously guaranteeing that the majority of GOG customers, who never see Sticky threads because they are cognitively acclimated to automatically & subconsciously ignoring Sticky threads since most of them are totally useless and also since there are way too many of them, would never see that Sticky thread, and thus be unable to answer GOG's question in the negative, as they surely would do if they did have the chance to see the Sticky thread and thus participate in the Poll.

I pointed out all the things I just said within that Sticky thread. But guess whether or not GOG corrected their biased behavior: no, they did not.

Instead, they left that thread as a biased Sticky thread, and they never made an equivalent non-Sticky thread either, thus GOG ensured that many/most of their customers would remain forever excluded from that Poll, and therefore GOG would receive only the biased answers that their loaded biased Poll was apparently designed to receive.

You know, I can't help but be blunt in saying that anything with your Patrick Star avatar attached to it, I can't take seriously since the character is a known simpleton.

If the survey links include bundled meta-data attached to it, that may violate what they said about the survey being anonymous and untracked and whatnot. But it's certainly not individual links, because that would absolutely violate the anonymity and multiple of us have gotten the same link too.

Not during the past few months. You didn't even add free games to your account :)
The number of games owned might be a indicator, maybe the account age. Or it was just purely random.

Possibly it's about behavior. €400 during Covid lockdown, but in 2022 I put a lot of things in my basket and then took almost all of them out again; I'd expect they'd want to know what went wrong.

I got an email for the first survey, but didn't respond to it before the link got reposted on the forum.

I'm not sure on what grounds you can claim it was a bad survey, any more than most surveys, perhaps all of them, aren't that good ... chiefly because people often say one thing but do another, and we are dealing with the limits of canned responses.

I was surprised at the length of the survey, and about halfway through nearly gave up. That in itself probably tells us something, chiefly that only those who cared strongly enough would persevere until completed.

As with all surveys there would be an agenda, and I personally think that at least half the questions in the survey were there to make it long enough and likely won't really be considered in the final analysis. The survey would have a psychological aspect, like they usually do, and perhaps one real important understanding of that, is that they want to obscure exactly what they are trying to find out.

I certainly wasn't happy with all the canned responses given, which made it hard to answer the questions at times, with me basically selecting the least wrong answer I guess. I'd even say there wasn't enough sense to a number of the questions.

I am guessing, and it is only a guess, that they decided on a number of customers to question, then proceeded to choose them from those that had spent the most money at GOG over a given time period. With that in mind, many customers could have been excluded, just because GOG had reached the study quota, not because a customer hadn't spent enough. Hell they may have even had a random aspect with a larger selection of good spending customers, until the quota size was reached.

For the most part good but some of the questions are severely limited, like sometimes it's not either "neutral" or "all inn". Would be nice to have one or more choices in between.

It's almost like in some games you can clearly see where the stamina/interest/time of the developers peak at the start and later towards the end it falls apart. :)