It is a very, very poor job done. I'm sorry to see this.
Cleaning yourself is an option, it is not very difficult with the right tools, but perhaps not this time.
There is a small hair in the right top corner, that should go with a blower.
If a blower doesnot get rid of the dirt, the best option is to use wet and dry sweeps.
The only REAL danger is having grains of sand or any other hard and scratching stuff on the sensor surface. Sweeping them would scratch the sensors surface and damage the camera.
Normally the chance of getting that kind of object stuck on the sensor is extremely low, however, since somebody has done this to your camera there is no way telling what it is that's stuck on there.
I'd advise you to:
- Have the camera cleaned professionally this time. It costs € 15 here in my local camera shop in Holland.
- Get yourself a proper set of cleaning tools, since this will happen to you again. If you can clean yourself, you will be self supporting when travelling.
Success,
- Bert