Marketa always has and always be a slick track, that's just the way it is. The track curators only know how to produce a slick track, and as a result that's what they'll get each year. You can't just pile dirt on a track and hope it sticks, because A, on a track build like Marketa is, the dirt will just fly off the racing line, and B, it's just not safe. The Marketa of yesterday will be the Marketa for the rest of the season, whether it's for Olymp Praha, or for the Lubos Tomicek Memorial later in the year. The track curators won't know how "piling dirt" (which so many of you suggest) will have on the dynamics of the track and the way it acts.
Yes I know that it's one of the worst GP's year on year, but there's not much the FIM can do about it, unless they want to have to build a track (a la Cardiff) in one of the stadiums in Prague (which from an economics point of view would be a disaster), or they completely scrap the Czech GP. Do we really want to see 4 or 5 GP's on Polish tracks each year?
Let's not forget, the Czech Republic is one of the few countries in the world where there is even a small bit of interest in speedway. Take away the GP and it's probably curtains for the already battered Czech Speedway circuit.