Hi Carolina
In the early 60's the Sombrero was used mainly by pseudo arty types and what you might call the beat generation. When it moved with the times it later became a mod hang out. Like all cafés and coffee bars of its time it had a reputation that very much exceeded its reality.
If you are hinting that it was a hang out of the Gay scene, then if so it was no more than any other coffee bar. It wasn't until very many years later that the area became known for that type of scene.
In fact I think in the early 60's if you wanted that sort of action it centred around Hurst St.
Phil