Both Whispersilk Cloak and Sudden Spoiling generate continuous effects (even though Sudden Spoiling says 'until end of turn'), so this situation is covered by rule 613. Interaction of Continuous Effects:
613.1. The values of an object’s characteristics are determined by starting with the actual object. For a card, that means the values of the characteristics printed on that card. For a token or a copy of a spell or card, that means the values of the characteristics defined by the effect that created it. Then all applicable continuous effects are applied in a series of layers in the following order:
613.1f Layer 6: Ability-adding effects, ability-removing effects, and effects that say an object can’t have an ability are applied.
613.2. Within layers 1–6, apply effects from characteristic-defining abilities first (see rule 604.3), then all other effects in timestamp order (see rule 613.6). Note that dependency may alter the order in which effects are applied within a layer. (See rule 613.7.)
613.6. Within a layer or sublayer, determining which order effects are applied in is usually done using a timestamp system. An effect with an earlier timestamp is applied before an effect with a later timestamp.
613.6a A continuous effect generated by a static ability has the same timestamp as the object the static ability is on, or the timestamp of the effect that created the ability, whichever is later.
613.6b A continuous effect generated by the resolution of a spell or ability receives a timestamp at the time it’s created.
Since Sudden Spoiling is cast after equipping Whispersilk Cloak, it has a later timestamp and it 'wins'; the creature doesn't have shroud. Therefore, it's a valid target for Condemn.
Sudden Spoiling targets a player, and therefore Whispersilk Cloak has no effect on it. In addition, since Sudden Spoiling causes all creatures the target player controls to lose all abilities, and Whispersilk Cloak grants abilities to the equipped creature, then Shroud would be lost and the creature can be targeted by Condemn (or any other targeted spell).