There can be several kinds of collisions in the markup:
Collision with content text is when you type something, intending it to be displayed as is, but it's being interpreted as part of the markup and interpreted accordingly. when this happens, you have to EscapeMarkup.
Collision with existing markup of the wiki in which Creole is being used. This is when both the original wiki markup and Creole use the same construct to mean different things. There are several solutions to this, usually involving disabling this feature either in Creole or in the original markup.
It's impossible to be CollisionFree with each and every wiki markup out there, but care should be taken to avoid the collisions whenever possible.
Collision with tradition and habits is when some construct is used in unintuitive way, against the rules popular in this context. This is unacceptable.