You can be red in the face; caught red-handed; red hot; read the red letters; get a red alert; but hopefully, you're not in the red.
Red is stop. That's become a deeply ingrained association with the colour, and relates in to a lot of the other meanings; particularly those of danger, or warning. The other two main associations with red are blood, and fire; the latter from which also stems the ideas of passion and emotion.
Common connotations with red are danger, alert, warning, stop, fire, heat, spice, passion, emotion, love, lust, shame, blood, death, sin, and often rose, or apple. The specific connotations may also depend upon the shade or tone; darker shades may be more reminiscent of blood and death, while lighter ones may be leaning towards passion and emotion.
To me, red more represents danger than passion. A warning; or something hot, like a fire. Flowers and food also come to mind - my mum is quite an avid rose grower; and red is quite common in tomato, capsicum, chilli, and some spices as well. Personally, it's not really a colour that I like that much, but that's also because I prefer cool colours. It is a lot better than a grey or black, though.
The song for today is Red Hot, by Jimmy Barnes. Bit of an oldie, but pretty good.