Paid advertising: Red flags
Each of these signals has a mechanism behind it. They are not "beware of cheap offers", they are specific things you can see in the document in front of you.
What to look for in the document in front of you
One number for budget and fee
If they are not separated you cannot judge either. This is the first thing to ask to have split.
Ads launched on day one
Without measurement in place first, the opening weeks spend money nobody will learn anything from.
A report of clicks and impressions
Both rise with the budget. Neither is a result.
A guaranteed cost per customer
The price depends on auction competition, which changes daily. The guarantee will either be broken or is worded to mean nothing.