Interestingly, since this thread was hijacked with silly & irrelevant talk of citizenship and assets, the OP (not surprisingly) hasn't been back. He last posted on EOS about 5 years ago, asking much the same thing, but was at that time about to buy a property in Spain.
In case he is still watching, I think the important thing to establish is, having bought a property, has he been submitting his non-resident tax returns regularly (modelo 210)?
Or, being in Spain more than 90 days, has he registered on the EU citizens register? Has he registered on the padrón at his local town hall? Is he a pensioner, and has he registered for free public health care? If he has done none of these former things, or anything else to alert the authorities to his potential status as fiscally resident, and as long as he has submitted his non-res tax returns, I imagine (as John pointed out earlier on) that there's little likelihood of the authorities being too bothered looking into the exact number of days he spends in Spain - or checking his mobile phone records! Perhaps he's being a little paranoid, or perhaps he thinks there's a good reason why they might be interested in him - only he knows. But also as John said, going to the Canaries for a couple of weeks won't achieve anything, so he should save his money if he was hoping that would avoid any potential tax liabilities.
Or he could talk to the wind. 