Technically, 'wind socks' are Wind Direction Indicators..........they're intended to provide you with a visual indication of wind direction, and not speed.
The 'Rules of thumb' for estimating wind speed from a dry wind direction indicator is that it's about 15 kts or above if the wind direction indicator appears horizontal, about 10 kts if it's 5 degrees below horizontal, and about 6 kts if it's 30 degrees below horizontal. If it's wet, then wind speeds are going to be a bit higher than for horizontal or the same deflections from horizontal when the wind direction indicator is dry.