The dirty secret of telemarketing is that it depends on using sleazy pressure tactics on vulnerable targets (e.g. elderly folks in the early stages of senility).
Someone with a legitimate product or service that has an actual target audience can sell it using normal advertising channels. Only crap and scams depend on telemarketing for viability.
it also seems that door to door selling is enjoying a comeback, and "no solicitors" signs don't help! Now they are trying to sell meat door to door...