Bright light negates concealment, which a scout requires to Hide under the god-awful stealth rules in the game.
But if the Scout has Hide In Plain Sight or something similar, he can still Hide, and he is still hidden.
The problem is the Light. Anything with regular sight (so not troglodytes, grimlocks, so forth) will see the Light, and know something is up. There are spells such as Dancing Lights, and creatures such as Light Archons, so it's not unreasonable that the monsters might assume that it's not a Plain Sight Hidden Rogue or an Invisible Wizard, but equally, there's no great reason for them not to assume it anyway.
TL;DR - Don't carry around a bright light if you are trying to be stealthy.
The Fix (is in): Cast Light on a Rock, toss the rock, have the Rogue tie a string to the rock, and drag/toss/kick it around with him. He's in darkness, monsters are lit up, everyone is sort of happy.
Rogue buys a wand of Dancing Lights, casts it using Use Magic Device, moves lights around to give himself sight but stays in the shadows. Enemies will know something is up, but not exactly where he is.
Rogue gets Darkvision. Via magic item, or spell, or whatever.
Rogue uses Listen checks to pinpoint foes, stumbles around in darkness somehow still being a stealthy, sexy, james bond lookalike.
Darkvision: Creatures with darkvision (orcs, goblins, most monsters) will see through darkness and see your rogue even in the dark within their native darkvision range (usually 60' or 120'). See: Godawful Stealth Rules.
The Fix: The feat Darkstalker from Lords of Madness allows a Rogue to use the Hide skill to hide from creatures with Darkvision, Tremorsense, everything that normally Auto-Detects a Rogue hiding. They need to roll a Spot check vs Hide normally, even though they have Darkvision or Blindsight or whatever. It is amazing.
Lesser Fix" From Magic Item Compendium, there is the cheapo Ring of the Darkhidden - for 2000gp it hides you from Darkvision (but not tremorsense and so forth) as if you were invisible. Invisible the status condition, not the spell, so it doesn't break when you attack. Note that you are not invisible to normal, light-based vision, or tremorsense, or any of that noise - just darkvision. So people can see you just fine by lighting a match.
Relephant: Sniping and the Hide Skill.