Scammer are too lazy for a normal work, They like to get rich quick without moving themselves. They are even too lazy to write a complete campaign offer with conditions. For this they are only writing a few words as caption and their phone number or email address from a free mailer like gmail. In the case they are writing their phone number they are even too lazy to add the country code.
Such an offer can get easily changed to a requested campaign of a center. The phone numbers are mostly prepaid phone numbers, which makes it much more easy for the scammer to disappear after he got some payments. The center has nothing to locate the scammer.
Conclusion: Don't try to make some business with someone, which is too lazy to provide all the campaign descriptions in their posting or on a separate website. Make a background check of your future business partner. If a background check is negative or not possible then forget the offer!
As more campaigns of one person or company are offered as higher is the risk to get scammed.
Forget offers, which are hosted on a free website like weebly or webstarts. Such offers are only for private people to make their family site. A real company will take the afford of a own domain and will not hide themselves behind a proxy service.