I couldn't give a flying toss whether Saints fans hate us or not. It just puzzles me why they reserve their hatred for us when they've been gang banged by Pool, the Goons and Utd.
I think it stems from jealousy, I see similarities in Spurs and Soton, we both like playing good football, both try bringing through the academy and both have loyal supporters BUT, I'd say we're just the next level up from them, which they can't stand. This isn't even meant as a dig but we are a better and bigger club than Southampton and I think that really annoys them and so it somewhat creates a little rivalry in their heads. After Pompey, I think Spurs are Soton's next biggest rivals.
It's quite funny really, as I was saying on my previous post about how I enjoy being hated, it's working out pretty well:
Arsenal - hate us the most.
Chelsea - hate us the most.
West Ham - hate us the most.
Soton - hate us the most in terms of Prem sides.
Liverpool - competitive rival in recent seasons which brings animosity between both sides.
Leicester - probably beginning to hate us

.
Everton - probably dislike us as we were once competitive rivals yet we progressed and they faltered, so jealousy there as well.
Aston Villa - probably cry at the fact they used to be competitive rivals with us and Everton and are now a shambles of a football club, probably hate us just because we're Spurs.
Stoke - when I left the Britannia a few years back, all I remember hearing was "cockney ****s wanna smash 'em!".