This all depends on how you define the term "ghosts," Fluffy. If by it you mean human spirits of people departed from earth, this was clearly real in the case of Samuel, but can be mimicked by demonic spirits as well. It's an interesting discussion.
But while it is an occult practice and clearly forbidden by God, the Biblical account suggests it really was Samuel she brought up.
3 Now Samuel had died, and all Israel had lamented for him and buried him in Ramah, in his own city. And Saul had put the mediums and the spiritists out of the land. 4 Then the Philistines gathered together, and came and encamped at Shunem. So Saul gathered all Israel together, and they encamped at Gilboa. 5 When Saul saw the army of the Philistines, he was afraid, and his heart trembled greatly. 6 And when Saul inquired of the Lord, the Lord did not answer him, either by dreams or by Urim or by the prophets. 7 Then Saul said to his servants, “Find me a woman who is a medium, that I may go to her and inquire of her.” And his servants said to him, “In fact, there is a woman who is a medium at Endor.” 8 So Saul disguised himself and put on other clothes, and he went, and two men with him; and they came to the woman by night. And he said, “Please conduct a séance for me, and bring up for me the one I shall name to you.” 9 Then the woman said to him, “Look, you know what Saul has done, how he has cut off the mediums and the spiritists from the land. Why then do you lay a snare for my life, to cause me to die?” 10 And Saul swore to her by the Lord, saying, “As the Lord lives, no punishment shall come upon you for this thing.” 11 Then the woman said, “Whom shall I bring up for you?” And he said, “Bring up Samuel for me.” 12 When the woman saw Samuel, she cried out with a loud voice. And the woman spoke to Saul, saying, “Why have you deceived me? For you are Saul!” 13 And the king said to her, “Do not be afraid. What did you see?” And the woman said to Saul, “I saw a spirit ascending out of the earth.” 14 So he said to her, “What is his form?” And she said, “An old man is coming up, and he is covered with a mantle.” And Saul perceived that it was Samuel, and he stooped with his face to the ground and bowed down. 15 Now Samuel said to Saul, “Why have you disturbed me by bringing me up?” And Saul answered, “I am deeply distressed; for the Philistines make war against me, and God has departed from me and does not answer me anymore, neither by prophets nor by dreams. Therefore I have called you, that you may reveal to me what I should do.” 16 Then Samuel said: “So why do you ask me, seeing the Lord has departed from you and has become your enemy? 17 And the Lord has done for Himself as He spoke by me. For the Lord has torn the kingdom out of your hand and given it to your neighbor, David. 18 Because you did not obey the voice of the Lord nor execute His fierce wrath upon Amalek, therefore the Lord has done this thing to you this day. 19 Moreover the Lord will also deliver Israel with you into the hand of the Philistines. And tomorrow you and your sons will be with me. The Lord will also deliver the army of Israel into the hand of the Philistines.” 20 Immediately Saul fell full length on the ground, and was dreadfully afraid because of the words of Samuel. And there was no strength in him, for he had eaten no food all day or all night. 21 And the woman came to Saul and saw that he was severely troubled, and said to him, “Look, your maidservant has obeyed your voice, and I have put my life in my hands and heeded the words which you spoke to me. 22 Now therefore, please, heed also the voice of your maidservant, and let me set a piece of bread before you; and eat, that you may have strength when you go on your way.” 23 But he refused and said, “I will not eat.” So his servants, together with the woman, urged him; and he heeded their voice. Then he arose from the ground and sat on the bed. 24 Now the woman had a fatted calf in the house, and she hastened to kill it. And she took flour and kneaded it, and baked unleavened bread from it. 25 So she brought it before Saul and his servants, and they ate. Then they rose and went away that night. (1 Samuel 28:3-25).
The poor children, especially young girls, who get preyed upon by demonic spirits pretending to be "Uncle Joe" or some friendly old codger are victims in the worst ways, however. Some end up getting raped by those demons if they are not strong enough to resist and do not call upon the Living God for deliverance.
So it all depends on who and what you are talking about.
