Yes. This is the safest option. Use either Satoshi-dice or Prime-dice, and stay away from the less reputed gambling sites. Most of the mixing sites charge as much as 5% or 10% as fee, while the same with gambling sites can be as low as 0.5% or 1% (on average, the "house edge"). But you should repeat this process two or three times, to make sure that the coins are "properly washed".