I think there is a mindset across majority of members when it comes to reporting low quality posts. After they have been reported it takes time for moderators to remove the posts if they deem them to be appropriate to remove and during the interim some might start tagging accounts (out of frustration and perceived lack of inaction to remove those reported posts).
As for 1xbit, they may have modified their posting requirements, I did not notice on their latest signature campaign application thread. I am honestly not capable to search through the forum for low quality posts because of what you described as a time-consuming nightmare but if most of us if not all did report more spam and low quality posts, it just might be more effective than we think.
Where to begin? I'm not familiar with how the 1xbit campaign operates; do they require posts in the gambling section? I've visited there more often than I'd like to whilst doing post history reviews, and some of the threads are thousands of pages long and growing by the second. I guess you could do reports if you suspect specific members (like Mamun74), but if you're going to be looking for shitposts by skimming random threads, that could turn into a seriously time-consuming nightmare.