In some discussions, I have often seen people who defend that it is not unreasonable to believe something without good evidence; then they, as a matter of consistency, claim that they will believe anything even if it has not been proven to be true (even though I don't believe that they are being honest most of the times). It is unreasonable and contradictory to accept every claim as true (i.e. believing anything at face value). Take the following claim:
1) Fairies exist.
If you believe everything at face value, you have to accept this proposition as true. Then you also have to believe the following claim as true:
2) Fairies-eating monsters that caused all fairies to be extinct exist.
Both of them are just assertions with no ground for support, but you cannot believe these two propositions at once, since they are contradictory. Therefore, it is impossible for someone to accept every proposition as true, or to hold a belief of every possible claim as true. Do not forget that, however, it may be the case that both 1) and 2) propositions are false.