What will happen if the throttle is not cleaned?

Since the carbon deposit is really like what you said, it is better to wash it, which will obviously improve the starting speed. However, washing in 4S costs a lot of money, so you'd better study it nearby and do it yourself in the future. As long as you have the corresponding plum blossom screwdriver and a can of carburetor cleaner, the cost is very low.

For details of Peugeot 206, please see Aika Auto /72/