sometimes they do until you actually render them... I have had others where if anything I couldn't even see the Spot... but when rendered it was completely blown where I thought the highlight was... That in a way is why I am in agreement about some of the comments Rykk has made on marbles in both Photoshop and UF... More natural in photoshop and not wrapped around the sphere.... Still I love to play with both methods
You very right you gotta test things first for sure since what you seeing on screen and the render may look different. I know I could apply the effects in photoshop or tweak them a bit haven't done that yet ...but it's an option.