This is an opportunity to show the difference in quality between "real" fonts and the cheap/free knock-offs that proliferate the free font sites.
Notice the uneven weight and bulging/choking strokes of Trekker compared to the even-weighted and smooth strokes of Crillee
Also, Trekker has very poor kerning and its finishing details (sharp, pointed tips of the serifs) are not something any self-respecting typographer would make.
And although it's probable you'd get away with using Trekker sometimes, it truly is downright ugly next to Crillee...