LOL – I just answered your same question over on sdlookup.com.

1) Staggered checks or checks for higher than the amount and get paid the “change” a week or so later.

2) You can look up the previous owner on the county records database site.
http://arcc.co.san-diego.ca.us/services/grantorgrantee/search.aspx

If you don’t know who the owner is – you can usually figure it out by plugging in the address to the property tax database

https://www.sdctreastax.com/ebpp3/(fbvk2bn0j131r0450qy1ts45)/Start.Aspx

(this will also tell you if property taxes are current.) Take the owners name from this tax record- and plug it into the grant deed search… You’ll see federal and state tax liens on that.

also look for mechanics liens, absentee judgements, etc… all red flags. I’m not sure – but I think judgements about unpaid child support can show up.

3) I think the 2nd gets wiped out at trustee sale. Fed tax liens must be settled, I’m pretty sure. So you should avoid properties that have these kind of red flags.