My last simple trick is one of the oldest in the books... checking the books. I think it is what the lawyers do when they check out the car before doing the traspaso paperwork. For this one we visit the fine Registro Nacional Público - Digital edition... If you don't already have an account, you'll have to register for a free account to get into the good stuff. Using fake info works if you're into that, but you will need to use an email account you have access to (like your fake email account!)
So take the Sistema de Certificaciones y Consultas Gratuitas link and login. Go to Consultas Gratuitas to find the Consulta de Vehículo link below Bienes Muebles. Again, if you don't know the answer to something, just select Particular! You should find a field to fill in Número de Placa and prove you're not a robot who somehow figured out how to login and navigate in Spanish to this useful spot.

Pay attention to the Valor Hacienda (¢3,620,000 in this case) and notice if their are any Gravamenes. Then click the Ver Persona link to find some details about when the car was bought by the current owner and more. You can check the Aranceles for Traspaso de Vehículos, for specific details, but I believe the easy way to calculate what it should cost if your lawyer doesn't try to stick it to you is, 3.5% of the Valor Hacienda covers impuestos and timbres (minimum ¢25 mil) and 2.0% of purchase price is how much you should pay the notario. This particular car was listed for ¢2,600,000. So 3.5% of ¢3,620,000 = ¢126,700 covers impuestos y timbres. 2.0% of ¢2,600,000 = ¢52,000 covers the lawyer for his efforts. Expect to pay ¢178,700 for traspaso plus any extra you want to toss your lawyer's way as a "tip". I'm not sure if that is still how it is calculated, but that is how I think it was done in year's past. The rule may be that the value you work off of is the higher of the Valor Hacienda and the actual sales price. A friendly lawyer might cut you some slack on that and use Valor Hacienda for the tax part and a lower sales price for their part.
When you take the "Ver Persona" link you can find out current owner details. Including when the car got registered in their name (Fecha Constitución.) In this case, they bought the car in July 2018 and they are already trying to sell it... Hmmmmm. Is that a good sign?
Anyway, there is so much public information available in the Registro. It can be a bit scary if you poke around. Use the Force for good and not for evil and everything should be okay! ;-)
After all the above due diligence has been done, still remember to have a trusted mechanic look over anything before you buy it. Some sellers have no shame. Just 2 months ago I know of someone who is very good at this who just bought a car with a hidden busted block. It is quite the bummer to have to replace a motor just 2 months after buying a new (to you) car. Pretty much you should assume any used car comes with a sticker which says: