Sometimes ethos, pathos and logos can be used to make people believe things that are not entirely true. can you think of an example? how can people avoid being tricked by faulty persuasion tactics?

Yes, all three make up the triangle of persuasion. 
Examples can be:

Ethos~ An advertisement on an alternative medicine persuaded to be efficient by the credibility of scientists in lab coats.
Pathos~ A commercial asking for donations to help abused animals to appeal to the emotional view.
Logos~ A statistic in a magazine about rates of how people with more shoes are more happy, suggesting you should buy shows for this reason.

Although all examples have bad motives for persuading, ways to avoid being tricked in these examples are:
-In ethos ex., people with lab coats aren't necessarily credible, look them up and see if they are legitimate, and if they are, look at what they are saying and if it is even relatable to the subject.
-In pathos ex., how did this commercial even get the money to be advertised? If they have money, they should use it to support the animals. Think before donating money to a program like this, because most of time, more than half the money you donate goes to them then the ones in need.
-In logos, the statistics are correct, but if you are depressed, it doesn't mean you should buy more shoes. There is a hidden variable in their data

I hope this helps?