Well my best (on 25 minute maps) are like 51-11 on prodigy (I would have a better K/D ratio if I didn't rush every round to get as many kills as possible - and this was on a dialup), 63-7 on inferno (cable), and then some retarded high ones on cs_deagle5 and awp_map. In DoD my best was like 128-5 on a dialup, but the other team sucked ballz and my friend and I would just rush and get the flags most rounds.
If you want easy good scores then log on early in the morning, like between 5 and 9. This is prime time for foreign players, and man do they suck, especially when they all have 300 pings on a U.S. server and you have a cool 50. I did it once and it was hilarious, you can rack up the knife kills. People from like Spain, Italy, Korea, etc. were all playing, and then it was me and a couple other guys from the states.