Ignorance is not a bliss in Islam. Islam encourages every muslim to know tenents of faith and basic fiqh.The higher Islamic science is Fard e kafayah , which means , it is compulsory upon the whole community to have some one who among them who can answer Islamic questions related with Tafseer , fiqh and hadith. One such Islamic science is the science of manuscripts. The scholars associated with this field have good knowledge of history, life of scholars , the type of arabic script used at different points in history, different works of scholars, their writing style and science of determining the age of paper etc.
This science becomes vital , as we know various works are attributed to scholars who did not compose those works. Some people used to ascribe their work to their teacher as a mark of respect ,others used to compose a work and ascribe the name of a famous scholar to increase its importance and still others used to ' add " additonal points in some one's other work, there by confusing general people.Some eveil people also used to compose work against Ahlus sunnah beleif and ascribe it to some great scholar of Ahlus sunnah to make people beleif that their deviant view is also held by this great scholar of Ahlus sunnah.
Many works are falsely attributed to Imam Ghazali and those scholar who studied the life and work of Imam ghazali , his writing style , his usage of words , grammar , and various reports coming from his contemporary scholars and also his next generation scholar are unanimous that these works are not from the pen of Imam Ghazali.
One such modern day scholar is Abdur Rehman Badawi, who compiled a book "Muallafat al -Ghazali in which he gave a detailed analyis of Imam gahzalis work based upon different exisiting manuscripts and also the research of other great scholars of Islam on this subject.
Another modern day scholar on this subject is Prof Mashhad al Allaf.
Prof. Mashhad al-Allaf has written a postscript to A. Badwai's work giving detailed reasons why the below works (1-9) are not works by al-Ghazali.
Reasons such as no mention in the texts of al-Ghazali's other works; language that is used in these works is not the norm that al-Ghazali uses in his works; mention of works by people that were born years after al-Ghazali had died; terminology that al-Ghazali never used in his other works; foul language that scholars such as al-Ghazali would never use.
LIST OF "PSEUDO WORKS" ATTRIBUTED TO IMAM GHAZALI (RH)
1)Sirr al-'alamin wa khasf ma fi al-dariyyan (Secret of the two worlds and unvieling what is in the two houses =worlds). [M:214; A:67,91; GAL no 31]
2)Mukashafat al-qulub (Unveiling of the Hearts) [M:239; A:239]
al-Madnun al-saghir, [M:107; A:40, 119] (Smaller [book] of secrets) also called:
3)al-Naffakh wal-taswiya (Breathing (life) and Formation (of creation). [M:107; A:107]
4)al-Ajwaba al-Ghazaliyya 'ala al-mas'il al-akhrawiyya. (Ghazalian Answers to Questions concerning the Hereafter.) [M:108; A:40]
5)al-madnun bi hi ala ghayr ahlihi [M:A:39] (controversial still!) however I moved it to the works page. I guess the jury is still out on this one.
6)ma'arij al-qudus fi madarij ma'rifit al-nafs. [M:76; A:76] (controversial still!) however I moved it to the works page. I guess the jury is still out on this one too.
al-risala al-ladunia. [M:50, 193; A:90] (translated by Godlas)
7)Minhaj al-'arafin (Methodology of the Sufis) [M:356; A:77, A:356]
8)Minhaj al-'abidin ila Jannati Rabbi 'l-Alamin (Methodology of the Worshipful Servants to the Garden of the Lord of All the Worlds) (possibly a summary of the Ihya') (planned translation by al-baz publishing, also published in India)[M:64; A:72]
9)al-Fara'id al-la'ali min rasa'il al-Ghazzali majmu`ah mushtamilah `alá Mi`raj al-salikin wa-Minhaj al-`arifin wa-Rawdat al-talibin, wa-hiya min anfas ma katabahu al-Ghazzali / [tashih] al-Shaykh Muhammad Bakhit, [Cairo] : Faraj Allah Zaki, 1344 
10)Risalat al-tayr (Epistle of the Birds) See article: Al-Ghazzali's Epistle of the Birds. N. A. Faris (PDF). [M:189; A:75]
11)ar-Radd al-jamil 'ala sarih al-Injil (The polite answer to the evident in the Gospels) (Arabic PDF) See article: "Al-Ghazali and the Arabic versions of the Gospels" Padwick, G. J., Muslim World 29(1939), pp. 130-140. Also in German: "Al-Ghazalis Schrift wider die Gottheit Jesu (Redd ül cemil)", Franz-Elmar Wilms, Leiden, 1966. [M:194; A:83]
12)Anwar hikmit [M: 91, A:103] (in Persian)
13)al-Durrah al-fakhirah fi khasf ulum al-'akhira. [M:62; A:66]
Critical edition: Le Perle Precieuse de Ghazali, ed. Leon Gauthier.
(the Precious Pearl) translated by Jane Idleman with an introduction. (PDF) (1979) Missoula, USA.
Die Kostbare Perle über todund Jenseits, übersetzt von M. Brugsch. Hannover, 1924.
14)A poem by al-Ghazali in Arabic. al-Qasida al-munfarija [M:255; A:255, 122, 434, 435]
Last words of al-Ghazali. (link)
15)Works on magic, talisman, witchcraft, litanies, dream interpretations, secrets of letters and numbers, etc. See A. Badawi's mu'alafat al-ghazali pp. 277-302(#'s 96-127) for more information.