Why does it seem like the cards are not random?

[bober2]

I frequenly find that at certain tables I may make 3 or 4 buy-ins, and I seem to hit my outs and draws repetitively at these tables. On the other hand there are tables at the same level and type where nothing I do can ever work: at these tables I lose my boats to better boats or quads, my 2-pairs are always beaten by straits, my opponant always has the nut flush, etc. I understand that some opponants are better than others, but still i have to wonder how the results can be so different and how it can be a random event that my cards always result in a second-best hand at certain tables.