I have a webpage that constantly ranks for keyword "Watermark software" at place #2. From time to time I also see it in the middle of the first page for "watermark images", but it appears there randomly. I don't see it there everyday.
Webmaster Tools report average position 2 for "watermark Images", but amount of traffic is very low and I suppose Webmaster Tools report is incorrect.
I signed up for semrush and their service reports my website ranks 32nd for "watermark images". This seems to be correct considering amount of traffic I get for that keyword.
The question is what is the reason for a website to appear randomly/sporadically in Google search results? Why do Webmaster Tools report incorrect position for that keyword?