This example illustrates the problem with phobias which is that the idea of the spider and what the outcome of a spider encounter is likely to be, is much bigger than the reality of the spider itself.
Of course with spiders, you can work round the problem. Someone else can use the broom to shoo it out of the bath or if you are on your own, you can simply keep out of the bathroom. But what would happen if you were about to realise a dream by moving to a converted barn in the countryside and the only thing stopping you is an encounter with a veritable Spider City?