Air Carrier inbound to SFO via the Tip Toe to Runway 28L executed a go around when traffic for the parallel runway apparently over flew the final. The reporter expressed concern regarding the ATC term 'follow' which was less than clear.

Narrative

While communicating with Norcal Approach; I was the Pilot Monitoring while we were cleared for the Tip Toe Visual approach into SFO; Runway 28L. Once on the heading portion of the published approach; ATC called out traffic on a right downwind which was about to turn right base. After questioning again the position of the aircraft; I called the traffic in sight. I cannot remember whether he said that traffic was for the right or left side; but he said to maintain visual separation with the traffic; follow the traffic; and maintain 210 KTS. I questioned ATC about the speed; since it looked like we were converging quite rapidly; and the communication was blocked. We were coincidentally assigned 180 KTS to the San Mateo bridge by ATC and told to switch to Tower. The First Officer and I were in constant discussion about the close proximity of the aircraft we were following on the right base leg. I felt we were getting entirely too close; and we had not even intercepted the localizer for 28L yet. We then were unsure which runway this aircraft was landing that we were following; and as we were debating a turn off of course to the left to go around; we received a TCAS RA 'descend' command which we complied with for a short time. Once satisfied that we were no in a collision danger; I instructed the First Officer to go around; and climb while turning left away from the traffic. I told Tower of our situation and asked for missed approach instructions; which we complied with. Cause; I believe the aircraft on right base overshot final due to a 30 KTS crosswind from the northwest; blowing him into our center line. We were however confused about which runway he was landing; and had inadequate time to query ATC as the event occurred quickly. ATC in SFO issued 'follow' instructions for aircraft landing the parallel runway; which is extremely confusing; and non-standard. Usually; 'follow' instructions are issued when following an aircraft to the same runway and not the parallel. This even was further complicated by the time of day; which was night time. Suggestions; I believe the other aircraft most likely overshot final; and that we should have been assigned a slower speed so that we were not both turning into each other while turning onto the localizer. Since we never even intercepted the localizer; I see no fault on our part.