Someone Somewhere said:
Putting a vacuum cleaner on low against where the air goes into your laptop is an option, but you get the most out of actually pulling it open.
What model is it? Some are quite easy to clean, though some are a bit harder.
I have a Satellite L675D-S7016 from Toshiba. Though I think I will stick to my current cooling method of an external fan blowing over it whilst it sits on a raised, ventilated platform.