Fixes alot of little errors.

Source/Game/Entities/Creature/Creature.cs

@@ -777,7 +777,7 @@ namespace Game.Entities
                 lowGuid = map.GenerateLowGuid(HighGuid.Creature);
 
             Creature creature = new();
-            if (creature.Create(lowGuid, map, entry, pos, null, vehId))
+            if (!creature.Create(lowGuid, map, entry, pos, null, vehId))
                 return null;
 
             return creature;
@@ -786,7 +786,7 @@ namespace Game.Entities
         public static Creature CreateCreatureFromDB(ulong spawnId, Map map, bool addToMap = true, bool allowDuplicate = false)
         {
             Creature creature = new();
-            if (creature.LoadFromDB(spawnId, map, addToMap, allowDuplicate))
+            if (!creature.LoadFromDB(spawnId, map, addToMap, allowDuplicate))
                 return null;
 
             return creature;

Source/Game/Entities/Player/Player.Spells.cs

@@ -255,7 +255,7 @@ namespace Game.Entities
 
         public bool CanSeeSpellClickOn(Creature creature)
         {
-            if (creature.HasNpcFlag(NPCFlags.SpellClick))
+            if (!creature.HasNpcFlag(NPCFlags.SpellClick))
                 return false;
 
             var clickBounds = Global.ObjectMgr.GetSpellClickInfoMapBounds(creature.GetEntry());

Source/Game/Entities/Player/Player.cs

@@ -2613,13 +2613,13 @@ namespace Game.Entities
                                 canTalk = false;
                             break;
                         case GossipOptionNpc.Battlemaster:
-                            if (creature.CanInteractWithBattleMaster(this, false))
+                            if (!creature.CanInteractWithBattleMaster(this, false))
                                 canTalk = false;
                             break;
                         case GossipOptionNpc.TalentMaster:
                         case GossipOptionNpc.SpecializationMaster:
                         case GossipOptionNpc.GlyphMaster:
-                            if (creature.CanResetTalents(this))
+                            if (!creature.CanResetTalents(this))
                                 canTalk = false;
                             break;
                         case GossipOptionNpc.Stablemaster:
@@ -3435,7 +3435,7 @@ namespace Game.Entities
 
         public bool IsAllowedToLoot(Creature creature)
         {
-            if (creature.IsDead())
+            if (!creature.IsDead())
                 return false;
 
             if (HasPendingBind())
@@ -4303,7 +4303,7 @@ namespace Game.Entities
                 return;
             }
 
-            if (creature.IsAreaSpiritHealer())
+            if (!creature.IsAreaSpiritHealer())
                 return;
 
             _areaSpiritHealerGUID = creature.GetGUID();

Source/Game/Entities/Transport.cs

@@ -377,7 +377,7 @@ namespace Game.Entities
             //         because the current GameObjectModel cannot be moved without recreating
             creature.AddUnitState(UnitState.IgnorePathfinding);
 
-            if (creature.IsPositionValid())
+            if (!creature.IsPositionValid())
             {
                 Log.outError(LogFilter.Transport, "Creature (guidlow {0}, entry {1}) not created. Suggested coordinates aren't valid (X: {2} Y: {3})", creature.GetGUID().ToString(), creature.GetEntry(), creature.GetPositionX(), creature.GetPositionY());
                 return null;

Source/Game/Entities/Unit/Unit.Combat.cs

@@ -1031,10 +1031,10 @@ namespace Game.Entities
             {
                 Log.outDebug(LogFilter.Unit, "DealDamageNotPlayer");
 
-                if (creature.IsPet())
+                if (!creature.IsPet())
                 {
                     // must be after setDeathState which resets dynamic flags
-                    if (creature.IsFullyLooted())
+                    if (!creature.IsFullyLooted())
                         creature.SetDynamicFlag(UnitDynFlags.Lootable);
                     else
                         creature.AllLootRemovedFromCorpse();