If a model has a goal up in their room for a certain amount of tokens then its up to the models if they have a certain amount of time to do that goal.

Some models will state that if the goal is not attained within a certain period they will move to a different goal.

This is not fraud if this is already stated.  This is why most models have a tip menu as to work towards a goal that they set for the room at that time.

Only if a model achieves a goal and does not complete that goal is when there is an issue.  BUT please note that some tippers will tip a model and say they are not tipping towards a goal & same with models, they will say that some tips that have been received will discount certain tip amounts for a goal.

This is all normally set out by the model.  If you are unsure if a model will do anything as stated above before you tip, then please ask the model first.