וְדָרַשְׁתָּ֧ וְחָקַרְתָּ֛ וְשָׁאַלְתָּ֖ הֵיטֵ֑ב וְהִנֵּ֤ה אֱמֶת֙ נָכ֣וֹן הַדָּבָ֔ר נֶעֶשְׂתָ֛ה הַתּוֹעֵבָ֥ה הַזֹּ֖את בְּקִרְבֶּֽךָ׃
(דברים טו:יג)
you shall investigate and inquire and interrogate thoroughly. If it is true, the fact is established—that abhorrent thing was perpetrated in your midst
Historically speaking, all of the accusations towards chabad have resulted in more free advertising. The irony is, litvaks dont even learn kabbalah in general let alone chassidus, and yet without even this basic level of investigation those who criticize simply remain naïve.
Rav Chaim Malinowitz ZTL (editor of Artscroll shas) actually gives a shiur on the first chapters of Tanya for those who want to educate themselves with an already verified source.