"Whenever there are mergers of two large customer-service providers ... we tend to see quite a few problems," said David VanAmburg, managing director of the American Customer Satisfaction Index, citing surveys about mergers between airlines, banks and other companies.
He said problems could be caused by hiccups in merging customer database -- things such as double billing or accounts getting lost.
"We'd be surprised if a new hybrid Comcast-Time Warner doesn't produce a lower level of customer satisfaction for a year or two," he said. "Customers have felt burned in the past by large mergers where choice is effectively reduced."
And it's not like a lot of people are in love with their cable service to start with.
Financial site MoneyRates.com released a survey Thursday in which 25 percent respondents called cable companies the worst for customer service. That led credit card companies at 15 percent, insurance companies at 14 percent and phone companies at 12 percent.
Past gripes about cable TV and broadband companies have focused on high rates and the difficulty of getting customer-service help over the phone, according to ACSI research.
Many consumers now pay more for TV and Internet service than they do for heat or electricity. Consumers in most areas of the U.S. don't have a choice between cable TV providers, which makes them feel helpless when rates rise or service is poor, VanAmburg said.
Would my cable offerings change?
In terms of services, this could be a win for Time Warner Cable customers.
If the deal goes through, TWC customers would likely be offered Comcast's wider menu of channels and services. While Comcast customers aren't necessarily satisfied all the time, a lot of its hardware and software has gotten high marks.
In its announcement of the planned merger, Comcast said that, among other services, it offers "50,000 video on-demand choices on television, 300,000 plus streaming choices on XfinityTV.com, Xfinity TV mobile apps that offer 35 live streaming channels plus the ability to download to watch offline later, and the newly launched X1 cloud DVR."
If the merger goes through, Comcast also would become the largest broadband provider in the United States. So Time Warner Cable subscribers would presumably have new options on that front as well.