However, If I search for "lazers" only 24 pics are tagged. This is a niche you can dominate.
Is that the niche of spelling mistakes? 
sure, why not? http://www.dreamstime.com/photos-images/lazers.html
Because it is not a niche if you use the correct spelling: http://www.dreamstime.com/photos-images/laser.html
So? The idea is to avoid tags with thousands of results. If you can find meaningful tags which lead to only a handful of images then you're laughing
But "lazers" is not meaningful! If you just make up words there are plenty of "niches" with 0 results...
It is meaningful to the person who typed it into the search box....remember these are real searches, not made up words. They may be typos or alternate spellings, but that is what these people were searching for.