CAM SEAL PROBLEMS in my Lexus 300

i had my cam seal changed 2 years ago because the dealer said it was leaking and now it’s leaking again. so they changed it out once more even though a cam seal should last much longer than that. the dealer said it should last at least 4 to 5 years.

so $600 later i get my car back and it leaks oil on my driveway and i can see an active leak under the car so i take it back and they realize they didn’t put the replacement cam seal right so they replace it again. Then they took a test drive and ran some diagnostic on it and the check engine light came on letting them know that there is a leak still. so they replaced it again or fixed it and i’m finally going to be receiving the car back today a week later but i’m worried that it’s going to keep happening and that other parts were damaged during all of the leaking.

so my two questions are:

1) how long should a cam seal really last?

2) should i have them clean all of the car parts that oil leaked onto?

thank you for your advice!

Yes, any oil saturated parts should be cleaned.
Normally, and unless an engine has been overheated, a cam seal will last the life of the car at the most or at least a 150k miles.

You should not be going through this many of them. If the cam seals have really been replaced and are really leaking, then about the only thing that could cause this would be if the cam surface that the seal rides on was grooved due to mileage. This is something that should be inspected whenver a seal of any kind on any car is replaced.
Another possible cause could be improper installation techniques or if the camshaft is loose on its stands/caps and moving around a bit. This could then wallow a seal out and is also something that should be inspected during seal replacement.
The latter one here is a possibility and only a faint one at that.

An area of concern would be an oil saturated timing belt. This will shorten its life.
I wish I could be of more help, but without seeing the problem firsthand about all I can do is guess a bit.
Bottom line is that you may have to replace a cam seal once; after that the car should expire before the seal goes out again. JMHO anyway.