You need to take into account that the bigger niche is the harder it is to beat competitors in the search engines, well not always it is the truth, but definitely most of the time. On the contrary, if you pick up the topic like the humiliation, it is a considerably smaller market, but it is way easier to good positions on the Google.
Also, you have to be careful with making any judgments by looking at the tags on the CB, because very often webcam models just use the most common ones for the exposure purposes. So for example, some use #bigtits tag even though they are flat chested, et cetera and vice versa.
I think it is better to search for the term like “big tits videos” on the Google and check out how much traffic the top sites get for this specific keyword.
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