Because of the high interest, and steadily rising prices of K98ks, the hobby is becoming less and less forgiving to those who don't care to take the time to learn and become students of the hobby instead of just accumulators. The accumulator is going to get burned.
There are plenty fakes, but 90% of them are not very good. 5% of them are OK, but wouldn't fool the regulars here. The remaining 5% are pretty good, requiring an astute and experienced collector to ID, which most can, with the highest end fakes requiring a hands on. The discussions here ferret out about 98% of the fakery. Certain types of K98ks (such as very late, unnumbered, reworks, etc.) lend themselves to fakery and some do not.
This is a great hobby if you want to be a part of something cool and learn. It is not for the uninformed or those with more money than sense.
Cheers,
HB