Had to visit the ROK over the last year a number of times over the past year. The "pay for sex" routine is pretty dismal compared to the rest of Asia. The best of the "legal" RLD's cater mostly to Asian males, aka the A row. This set of "windows" on the main street contains some very hot women, but unless you're asian and speak passable Korean. You are out of luck. You can get some action in the "B" row (back streets), but the old ladies (ajima's) will sometimes rip your arms off. Sex here is pretty much wam bam thank you mam at ~$60 USD.

The other alternatives are massage establishments which pretty much run the same rate as US parlors (but the women are a tad bit nicer), and the "Hill" in Itaewon. Stay away from the Hill unless you are well informed. The girls here are experts at taking your money and want $300 USD for a short time (although you can get them lower).

Rather than try for "pay for fun", I've taken the the pick up route. I've made four trips to Seoul in the last year, and I scored on the first three at Gecko's. Gecko's is a standard bar in the foreigner district of Seoul. American military will hang out there until their curfew (1am on Weekends), and there is usually a reasonable assortment of single Korean women looking to score with a western guy. As I said, my first three trips I was able to bring a girl back to hotel with me. I wasn't lucky on the fourth trip. I think primarily because of some growing tensions between the Koreans and American military located near Itaewon.

Having Said I've been lucky- I speak a fair amount of Korean, and I'm reasonable looking. The two seem to let me be more successful than the average monger.