Best to assume anyone asking for contact details before buying is going to be completely full of shit. They don't have the intent, nor the means to make any investments and will fuck your brain with 99 questions, try to set abnormal conditions or contingencies involving third/fourth parties (delaying deals until reaching "clients" or "team"), etc. The reality is there are very few circumstances where anybody has a valid reason to take communication off-platform. If sensitive details require, then private message, open the guarantor, and fuck all the extra!