Yes, many Farangs have no balls to buy Viagra or 'Juice' in local Pharmacy, they think they'll get busted.
Enjoy 
Technically, being caught with Kamagra gel or Viagra is an offence in Thailand, it's a controlled substance and actually requires a prescription, even though the pharmacies and some vendors still sell them. Same with xanax.
So if travelling around, I would avoid having these on me, because sometimes police do spot checks on farang, and if they're difficult it could be an issue, even though quite unlikely.