Yes I've used them in several different countries and with fairly good success.
I met my ex-wife in China and while the marriage didn't work out there was nothing wrong with the site (ChinaLove)
I used ColombianCupid a great deal when I lived there with fairly good results I dated a number of girls and found some very good ones. I also learned Spanish, which was my main intent.
When I moved to the Philippines last march I switched to FilipinoCupid with good result and met my current GF with this site. We have been together for over 6 months and all is well so far.
All that said I have also ran across endless numbers of liars, cons & theives.
There are the Nigerians or Ghanians that I've run into, a lot of fun if you are aware and realize what they are. I can lead them on and make them dance through hoops then cut them off by letting bthem know that you know exactly who they are and what they ate trying to do.
I've heard from friends that dating site in the US are among the worst after Russians which are predominantly cons.
So here are a few rules to follow.
1. look for sites that have monthly unlimited rates rather than per letter charges.
2. After you have made contact switch to a non-affiliated service like Yahoo or MSN messenger.
3. Before you consider meeting someone do a couple of video calls to see if the match their photos.
4. Ask direct questions that you know the answers to straight off so you don't waste time.
5. Read the person's entire profile before you initiate a conversation. If they start the chat with you read it while you chat. Look for inconsistencies in what they say vs their profile.
6. Never under any circumstances send money or give personal details that could be used against you.
7. Use a screen name until you feel you know them well enough.
8. Don't place personal information in your profile that would allow someone to trace your location.
9. When you meet someone for the first few times do it in a public place and under no conditions get into a vehicle with a stranger. Remember that Ted Bundy looked like a nice guy.
There are a lot of good people online and it beats the hell out of hitting bars or clubs but it is a buyer beware situation for sure.