Yeah I normally travel with multiple bodies just in case of this and have had dust find it's way inside one that hasn't had the lens changed before. Obviously environment plays a part, that said I got lucky in Africa and despite the entire outside (and within focus ring on a 24-105L) basically turning brown the sensors stayed clear. 60D+7D at the time for what it's worth - and the 7D was a lot better at staying clean.

If I'm away, I'll resort to trying to blow it if serious. At home I will and have successfully used swabs a few times. I don't recommend doing this the night before a flight even though I got away with it, and be sure you're doing it in a very clean location (which includes not 5 minutes after vacuuming as there will still be dust floating). I trust myself more than I trust shops here; but again you want to go into it with multiple spare swabs in case you need to do it a few times.

You can pick up some cleaning fluid and clean swabs for less than the cost of a single cleaning. It is kinda stressful the first time though.