I had almost $80K once in paypal without any problem. My observations:
1) Too many small transactions (< $50) can trigger alert in paypal system (leading eventually to account limitation/review)
2) Few large transactions (> $10K) can trigger alert in paypal system
3) Quickly withdrawing money as soon as it is received in paypal will trigger alerts
4) Logging into your account from multiple locations (geo IP) can trigger alert
5) Logging into your account from an IP which was used to login to another limited account will trigger alert.
I used this (and another account) for receiving payments from my clients over a two year period without any problems. Amount varied between 1K to 15K per transaction.
My accounts got limited when I received a large payment and tried to withdraw immediately. I did get my money after waiting 180 days (I didn't want to submit any documents to remove limitations).
All my transactions were genuine
Hope that helps