Its cheaper to skim it than throw loads of adhesive at it , quicker to tile if can gauge
Is a bit rough i wouldnt want to tile it
Doesnt need to be polished skim for paint can do it yourself
Should be able to knock those adhesive blobs off from the previous dot and dab tiling (considered of the worst type of tiling going). Then apply adhesive using a trowel next time and you wont get those off so easy.